The movie begins in 1938, during the Spanish Civil War.
One day, German SS troops arrive at a small village during a wedding.
They offer the SS officer in command a drink of Schnapps, which the wedding guests are
drinking, but he coughs and sputters, causing them to laugh at him.
Embarrassed, he orders his men to fire with a machine gun, slaughtering all the wedding
guests.
The SS men put on gas masks and release several canisters containing strange blue gas over
the corpses.
Meanwhile, a blindfolded man stands before a firing squad for his execution.
He tries to save himself by explaining that his uncle is a high-ranking general, but they
ignore him and prepare to fire.
Fortunately for him, his uncle arrives and intervenes in his nephew Jan's execution.
Jan's uncle, General Lozano, says it's the third and last time he will save his life.
He has convinced the Francoists not to execute him.
In return for sparing him, the regime wants Jan to deliver a message to General Alarcos,
a unit commander in a dangerous area of the front.
They are punishing him because Jan is a lawyer who helps many deserters evade punishment.
To prove he's a good soldier, he must go on this suicide mission.
Private Decruz, a deserter Jan had saved, is assigned to be his driver for the dangerous
mission.
Before leaving the base, Jan encounters a wounded friend on a stretcher.
As an act of kindness, he lights his cigarette before the nurses treat him.
The same SS troops from earlier supervised the transfer of the wounded nationalist soldiers
onto a train, claiming to give the soldiers prostheses.
Soon, Jan tells Decruz to take a shortcut through a valley where both sides are fighting.
They unexpectedly come across German soldiers building a roadblock.
The German officer tries to stop them from passing, but Jan subtly threatens him into
letting them through.
During the drive, Jan asks Decruz why he joined the war.
Decruz explains that his village is famous for delicious pastries made by nuns.
He joined the Francoists so that the Republicans to save the nuns, to ensure the safety of
the treats.
As they pass through the valley, Jan and Decruz see an Italian Fiat fighter shot down by a
Soviet Polikarpov fighter.
Spotting a parachute from the Italian aircraft, Jan decides to take a detour to rescue the
pilot, much to the dismay of Decruz.
They soon reach a clearing and discover the mangled corpse of the Italian pilot.
Before they can return to their mission, a group of Republican soldiers emerges from
the forest and captures Jan and Decruz.
The Republicans search for Jan and discover that the message he was supposed to deliver
is meaningless.
They threaten to kill Decruz, but Jan lies and says he has a wife and two kids.
The Republicans decide not to kill him and instead capture Jan and Decruz.
The photographer stays behind to take a picture of the dead Italian pilot.
Still, the pilot suddenly returns to life and bites his neck, killing him.
Two Republican soldiers, Brodsky and Mecha, rush to help and throw the corpse away.
However, the zombie starts attacking them by crawling toward Brodsky.
Brodsky shoots it with a submachine gun, but it does not stop.
Just as the zombie is about to bite Brodsky, the Sergeant kills it with a shot to its head.
The photographer's corpse then gets up, surprising Mecha, who thought it was dead.
It attempts to attack the group, so they shoot his head.
The group leaves the area, witnessing Junkers bombers flying overhead as they move.
The group hears explosions and discovers the destroyed Republican camp.
They observe that the dead Republican soldiers in the camp have come back to life.
Carlos, one of the Republican soldiers, sees his father among the reanimated soldiers and
tries to talk to him but gets attacked and killed instead.
The Sergeant does not want to shoot their comrades, but it appears that they are no
longer human.
The remaining Republican soldiers start shooting at the zombies, realizing that hitting them
in the head is the only way to kill them.
With this information, the group manages to escape and find a nearby boat.
They travel on the river, and the Sergeant suggests going to a safe house in the mountains
where they can radio for help and learn what has been happening.
They also decide to have a temporary ceasefire from fighting in the civil war and focus on
surviving the zombies.
They dock the boat then they are attacked by more zombies.
The zombies bite Brodsky, and having no choice, the group continues fleeing until they reach
a small cabin.
Inside the cabin, they find a pair of Nationalist soldiers, Jurel and Rafir, and a nun, Sister
Flor.
A standoff ensues, and Jan manages to stop them by convincing the two sides to call a
truce.
The Nationalist soldiers explain that a Junkers aircraft accidentally attacked them, resulting
in the death of most of the patrol, and the reanimated dead immediately attacked them.
They found Sister Flor along the way while going to the cabin.
They decide to stay and rest in the house for the night and split the ammunition and
food.
The group spends the night talking about what's happening, their lives before, and the war's
situation.
As the night wears on, the group becomes more comfortable.
Jan catches himself staring after Matacuras, the female Republican, while the Sergeant
feels drawn to the nun.
Jaime, the Republican unit's commissar, pulls out the telephone from the cabin and tries
to contact someone.
Jan sits by the fireplace and burns the paper that his uncle gave him.
Then, a map begins to appear on it.
While Matacuras is in the bathroom, Jurel corners her.
He tries to intimidate her into sleeping with him.
She explains that she has a reputation for being a priest-killer because she tortured
the priest who abused her little sister, which scares him away.
Suddenly, they realize a large group of zombies is approaching.
They quickly run out the back while the zombies invade the base, and Mecha uses dynamite to
cover their escape.
The group discovers a large fence with electrified barbed wire.
They see that the SS had fenced off the entire area.
They notice some zombies stuck, including a zombified Brodsky.
Jan takes the initiative and kills him, sparing the Sergeant from the task.
Jan discloses that his uncle entrusted him with a letter containing a secret map written
in invisible ink.
The group decides to explore the central area of the map, where the base is.
They discover that the base is, in fact, the remains of the village the SS destroyed earlier.
The ruins bear the same blue powder they found from the dead pilot.
While they explore, they encounter a survivor named Ana, who survived the attack by seeking
shelter behind her husband's body.
Ana explains that the SS took over the town and conducted experiments until an accident
happened, leading to the destruction of the SS unit by additional zombies.
Meanwhile, Jaime searches the church and discovers the formula the Germans used.
He plans to bring it back to the Republic to use against the Nationalist-held cities
and win the war.
Outside, Decruz is fixing a truck, trying to jumpstart it, then he hears the zombies
approaching.
The other Republican soldiers object to Jaime's plan, leading to a standoff.
Decruz bursts inside, frantic about the zombies approaching.
Jaime takes Decruz as a prisoner and backs away, scolding the other soldiers.
Suddenly, he's swarmed and killed by a group of zombies.
The reanimated corpses try to break into the church, forcing the group to escape through
tunnels.
As they flee, Jurel assists in carrying Ana, unbeknownst to them, is infected, and she
attacks him.
During the fight, Rafir appears bitten by her, but fortunately, Ana's teeth do not penetrate
his boot.
After defeating Ana, the group continues to run.
Sister Flor chooses to stay behind, revealing that Ana bit her in the leg, and she intends
to stay and take care of the zombies.
Outside, Jan suggests going to Las Aguilas, hoping to stop the plague, revealing that
his brother is fighting for the Republicans.
Jan finally understands from the map that the Francoists and Germans plan on spreading
the blue powder to the rest of the country.
Jan doesn't want that to happen, so he informs the group that they should go to the outpost
where the Germans are preparing trains filled with blue powder, as he believes they have
an antidote.
The Sergeant reluctantly agrees, but only on the condition that when they get captured
after everything, he wants his comrades to be pardoned, and he will take on the punishment
of death himself.
Decruz appears with the truck, and they drive to the outpost.
Jan walks alone to the gate, where he meets his uncle and the SS German officer.
Jan's uncle reveals he knew what was happening and that the Soviets are working on a similar
bioweapon.
The Francoists do not care that people will die, and they plan on bombing the entire valley
anyway.
Jan refuses to leave the rest of the men behind and returns to the group.
Jan's uncle is murdered by the SS when he tries to delay a bombing raid on the valley.
Later, Decruz reveals he got bit while retrieving the truck.
He intends to carry explosives and trigger them to blast a hole in the roadblock.
Jan tearfully says goodbye to Decruz.
Decruz walks to the outpost alone, and the soldiers kill him.
He then rises as a zombie and successfully triggers the explosives.
The group enters the base, but a zombie horde hears the loud noises and follows them.
The large group of zombies enters through the tunnels into the outpost, and they begin
slaughtering the Nationalist and German soldiers defending the base.
Jurel deserts the group inside, and Mecha takes off on a motorcycle.
They make their way through, searching for a train car where the SS must have set up
their laboratory.
Rafir climbs on top of a train car and provides sniper support for the group.
He also saves Jurel, who has become surrounded and cut off.
A zombie suddenly attacks Rafir from behind, and he appears to be killed.
Jurel locks himself in a truck, and seconds later, Mecha climbs inside.
The keys are not inside the vehicle, and the two men are trapped.
Knowing their deaths are at hand, the two men set aside their differences and share
a moment of comfort.
With only seconds left before the windshield breaks.
They discover a large crate in the back of the vehicle containing explosives.
Then, Mecha reveals he has a single stick of dynamite.
They sacrifice themselves, killing many zombies in the ensuing explosion.
The Sergeant tries to start the train while Jan and Matacuras are inside the train car
laboratory to find an antidote.
Inside, they encounter the SS commander, who declares no antidote and injects himself with
blue liquid to become a zombie.
Matacuras shoots the SS officer in the head before he fully transforms.
A zombie unexpectedly bites Jan's hand, so she cuts off his hand, preventing him from
becoming fully infected.
The Sergeant manages to get the train moving, although he shoots himself as a large group
of zombies close in on him.
The train, however, successfully escapes the base as the bombs befall the valley.
Matacuras and Jan lock themselves in a steel box as zombies rush toward them in the train
car, and they share a kiss as the bombs rain down.
Rafir, on the back of the train, has survived as well.
Later, Matacuras brings Jan back to the edge of fascist lines, and she tells him her intention
to slip over the border into France as they have lost the war.
They say their farewells and go their separate ways.
The movie ends amongst the train wreckage as a scream is heard, indicating that one
of the zombies may have survived.