In 1862, English nurse Elizabeth travels to Ireland after serving in the Crimean War.
Once she's found a room in a local inn, she goes to see the village's council, formed by
Doctor McBrearty and other important local men. The story they have to tell is quite amazing:
the O'Donnell family, who live outside the village, swear that their daughter hasn't eaten
anything in four months yet she continues to be healthy. This has caused tourists and journalists
to come from all over to visit the miraculous girl, and the council feels the village is being
mocked in newspapers. Elizabeth will be working with Sister Michael to keep an eye on Anna in
order to discover if there truly is a miracle going on or if it's all a trick. That said,
it's forbidden to force Anna to eat, but she can be fed if she asks for it which hasn't happened
so far. Elizabeth and Sister Michael will take turns in eight-hour shifts, and they can't share
information with each other, then in two weeks they shall bring separate reports to the council.
Afterward, Doctor McBrearty takes Elizabeth to the O'Donnells' house, and on their way there,
Elizabeth wonders why they didn't hire two nurses. The doctor explains the family is deeply religious
and was more accepting of the idea if someone of faith was involved, many of the council members
that were less scientifically inclined also voted for a more religious view of things. At the house,
Elizabeth first meets Anna's mother Rosaleen, her father Malachy and her sister Kitty,
but she can't see Anna yet because there are visitors, so Elizabeth takes the chance to
ask questions about the kid's medical history, although there isn't much to say. Anna is healthy,
perhaps just a bit delicate, and never shows any signs of appetite. Elizabeth points out that this
watch could better be conducted at a hospital, but the family refuses to let them take Anna away.
Once the curious tourists finally leave after dropping some money for the family as thanks,
Elizabeth gets to meet Anna at last and finds her in the middle of praying. Elizabeth gives Anna a
full check-up, and after taking some notes, she asks the girl some questions, but Anna doesn't
look or act nervous. She swears she doesn't need to eat because she leaves off manna from heaven,
and it's enough to make her feel full. During lunch, Anna still sits at the table and watches
the others eat. Elizabeth finds a family picture that includes a son named Pat and learns he isn't
in the house because he died. The O'Donnells ask Elizabeth about her own family, and she explains
she's a widow, although she doesn't mention she also lost a baby. At the end of the day,
Elizabeth changes places with Sister Michael before returning to the village. Before going
to sleep, Elizabeth drinks a special medicine and pricks her finger while staring at the shoes of
her lost baby to spark up her mind and forget about her sorrows for a while. From then on,
Elizabeth spends every day with Anna and saves her nights for her sparking medicine. Soon they
enter an easy routine that allows Elizabeth to get to know Anna better, like the fact her main
hobby is collecting religious cards. Elizabeth starts taking Anna out for a walk every day, and
at least Anna accepts to take some water when they do. She also wears her brother's boots to remember
him by. Whenever she has the chance, Elizabeth inspects every nook and cranny in Anna's room,
but so far, she hasn't found any proof of foul play. Sometime later, when Doctor McBreary comes
to check on things while yet another journalist named William takes a picture of Anna, Elizabeth
takes the chance to protest against these visits. Anna is constantly being bothered by strangers,
and for a serious study, quiet and isolation would be preferred, thus the doctor accepts her request.
Later at the inn, William approaches Elizabeth to ask permission for an interview, but Elizabeth is
firm on not allowing any strangers to visit Anna, and she refuses to answer any questions because of
patient confidentiality. As time passes, Elizabeth continues to search for clues. She asks Kitty
what was the last thing Anna ate and learns it was Communion bread because she has her Holy Communion
on the same day as her birthday, which the family considered a blessed day; Anna had stopped eating
exactly when she turned eleven. Elizabeth also asks Sister Michael to change shifts so she can
watch Anna over the night and asks for a lamp to be brought to her room for better light, this is
how she learns that every night Anna's parents come to say prayers with her and part of this
ritual includes Rosaleen kissing Anna's mouth. While Anna sleeps, Elizabeth checks the bottom
of one of Anna's treasures and accidentally breaks it, but it also allows her to find a lock of hair.
The next morning, Elizabeth apologizes to Anna for the accident and confirms the hair used to belong
to Pat, but when she asks Anna if she misses her brother, she only answers that sorrow is God's
spade and it readies the ground. Also since Anna keeps insisting on giving Elizabeth a nickname
instead of calling her Mrs, Elizabeth decides to give her one in return. Anna doesn't like it
at first because she feels like someone else, but after Elizabeth mentions a bunch of options, she
uses Nan and Anna decides to keep that one. Days continue to pass with Anna not receiving visitors
anymore, only Elizabeth, Sister Michael, and her family are allowed to see her, yet William stays
in the village, unwilling to give up on his story yet no matter how many times Elizabeth turns him
down. William confesses he still sends his editors daily updates, vague as they may be, and when he
calls Anna a good actress, Elizabeth shocks him by saying she believes Anna's sincerity. Elizabeth
regularly checks Anna's health to take notes and doesn't mind telling her stories about the war
when the girl asks, but Anna often disturbs her by replying with creepy imagery from the Bible. One
evening, Elizabeth finds Anna's family surrounding the child for their daily ritual and it raises
so many red flags that it prompts Elizabeth to announce not even her relatives can approach Anna
anymore, from now on only she and Sister Michael can touch her. The family doesn't take this well,
but they still continue to bring Anna her daily prayers by standing on the stairs. When William
approaches Elizabeth again saying he could be the fresh eyes she needs to crack the case,
Elizabeth turns him down explaining she's keeping the family away and that should reveal the truth
soon. Hearing this worries William because that means Anna won't be getting food for real now,
and there's no way the family will confess because then they'll be either arrested or
kicked out for concealment, conspiracy to fraud, and misrepresentation of God's will. Unfortunately
William's worries soon become a reality: the next time Elizabeth checks on Anna, she discovers she's
lost a tooth. One afternoon, while Elizabeth is making her way back to the village, she's
approached by Kitty for a little chat and finds out William used to live here as a kid before
he left for London to study. His family died in the Great Famine after they locked themselves
up in their house to avoid public humiliation, and William hadn't been there for them. When Elizabeth
returns to the inn, she realizes William is the only that understands the grieving pain she's
going through, and they end up getting together for the night. After they're done, Elizabeth
explains she isn't actually a widow: when she lost her baby, her husband vanished, so in her eyes he
may as well be dead. From then on, Elizabeth allows William to come to the daily walks
with Anna, that way he can satisfy his curiosity without anyone else getting ideas about breaking
the rules. For now though, William doesn't ask any intrusive questions and opts instead for sharing
stories about all the countries he's visited for his job. Sadly things don't get any better:
Anna is getting weaker and is constantly tired. Elizabeth allows at least Kitty to enter the room
again and has a talk with the parents, asking them to force Anna to eat, but they refuse because Anna
made them promise on her birthday that they would never ask for such a thing. Desperate for help,
Elizabeth goes to see Doctor McBrearty, but he pays no attention to her warnings because he sees
this as a necessary experiment. As Anna gets worse every day, Elizabeth finally snaps and brings
a medical hose to force-feed Anna some soup. However when she notices Anna is crying in pain,
Elizabeth quickly takes it out and apologizes for her outburst. Anna understands and is so kind
about it that when her mother asks what were those noises about, she doesn't snitch. One afternoon,
Anna begins having trouble breathing while having the daily walk, but she refuses to go back to the
house because she wants to show Elizabeth and William the little lake near her house that
she calls the Holy Well. This extra effort makes her pass out so Elizabeth rushes her back home,
where Rosaleen tries to indirectly ask her daughter if she wants food, but Anna still
turns her down and promises she just needs to rest. From then on, Anna coughs often and
has constant trouble breathing, thus she begins moving around in a wheelchair brought by Doctor
McBrearty. After a night spent comforting Anna because coughing wouldn't let her sleep, Elizabeth
is having lunch on her own and her obsession with the case finally lets her have a revelation. She
rushes to see Anna and tells her the sacred manna she thought she was consuming through god had been
chewed food her mother fed her through the kisses during their rituals, but Anna refuses to see it
as food. Because it was part of the ritual, it still counts as a holy secret, but Elizabeth
will never understand because she doesn't share their beliefs. Even if the truth is out now,
Anna refuses to receive food or those kisses again because she's been fasting on purpose to save her
brother's soul. It turns out Pat took advantage of Anna since she was nine, calling it "double love"
because she was both a sister and a wife to him. Rosaleen blamed Anna for Pat's despicable actions
and now Anna even admits she loved him too, that's why she's fasting - usually religious fasting is
only for a day or two, but Pat's soul must be terribly deep in hell for his actions. He died of
a mysterious disease that Anna thinks was a sign of God's wrath, so she must make a sacrifice to
save Pat's soul from damnation. Elizabeth tries to explain to Anna that nothing was her fault and how
damaging can it be to think like that, but Anna is firm on her decision. When the time comes to
present her report to the council, Elizabeth tells the men that Anna is dying and that her
mother had been feeding her through those kisses like a bird. The council doesn't believe her
because they've seen an article written by William saying Anna's death will be the responsibility of
both the parents and the community and therefore murder, so they think she's making up facts to
back up his story. When Elizabeth protests, they ask Sister Michael for her opinion, but she denies
having seen those kisses. Elizabeth accuses her of lying, and the council decides to bring Anna in as
a tie-breaker, but she denies it all as well. The council allows Elizabeth to continue her watch,
but now she's thought of as a fool by everyone. Anna's condition continues to get worse to the
point where she throws up even the little water she drinks. Elizabeth tries to reason
with Rosaleen, telling her to give those kisses to Anna again, but Rosaleen refuses - she doesn't see
this as losing Anna, she thinks she's working toward her and Pat's salvation. Rosaleen is
at peace because she's sure her children will go to heaven. On Sunday the family will be at mass,
so it's Elizabeth's last chance to do something. She asks William to help her kidnap Anna in order
to save her life and William refuses because he thinks they should respect the parents' beliefs.
Elizabeth finds this incredibly hypocritical because he had no trouble using the word murder
in his article and points out that if William doesn't want to run away with them to start a
new life as a family, he could at least help them reach the city safely. Moments later,
Elizabeth begins taking fake notes in her notebook while the parents and Kitty leave for mass. When
Anna begins having the worst trouble breathing so far, she realizes her time has come, but Elizabeth
approaches her with a new concept: she could let Anna die, but a new girl could be born from that
sacrifice, a girl called Nan that is nine years old again and never went through anything bad.
Anna likes the sound of this because part of her would still go to God, so Elizabeth takes her on
the verge of death to the Holy Well and guides her through a ritual where Anna closes her eyes and is
unconscious for a few seconds. When the girl wakes up again, Elizabeth tells her she's Nan now, and
finally gets to feed her. After letting William take Nan away to hide her, Elizabeth returns to
the house and, after putting away her notebook in her pocket, she burns the building down together
with her own medicine and her baby shoes. Now that she has Nan, she won't need them anymore. To make
her story more believable, her hands get burned too. Sometime later, Elizabeth presents to the
council her notebook with fake notes about Anna getting worse and dying naturally, explaining
that the shock of Anna's death made Elizabeth so upset she accidentally knocked off the lamp and
started the fire. The council is skeptical because a body couldn't be found, but since they have no
evidence to accuse Elizabeth of anything, they let her go without payment for failing her task.
Later when Elizabeth is getting ready to leave the village, Sister Michael approaches her with
the excuse that she wants to help her change her bandages. While doing so, she speaks in code and
tells Elizabeth about a vision she had of an angel taking Anna away on a horse, obviously meaning she
saw William doing his part of the plan. Sister Michael doesn't snitch on her though, she just
wants to be sure Anna is in a better place now, and Elizabeth confirms she is. A few days later,
Elizabeth travels all the way to Dublin, where William is waiting with Nan, who is already
looking much healthier. Using fake papers, the three of them pose as a family named Cheshire and
board a ship to Sydney, where Anna is comfortable enough to finally introduce herself as Nan.