In France, 1890, Doctor Cachet and Madame Venet try to get through to Vincent Van Gogh, who is sobbing hysterically. They look at his newest painting and wonder what it is.
In the Cabinet War Rooms in London, 1941, Professor Bracewell takes a recently discovered Van Gogh painting to Winston Churchill. They realize that it's a message, and they know who it's for. All they have to do is deliver it.
At the Stormcage Containment Facility in the year 5145, a call comes in and River Song hears it from her cell. She demands the right to take it and the guard hands it over. River expects the Doctor, but it's Winston Churchill. The TARDIS has rerouted the call. He passes on the message and River then turns to the guard to turn over the phone. When he admits that it's his first day, she pulls him toward her through the cell doors and kisses her. The guards arrive to find the guard suffering from a hallucination that River is still in the cell.
At the Royal Collection in 5145, River breaks in and finds the Van Gogh. She takes it and starts to escape, only to find Liz Ten waiting for her. River explains that it's about the Doctor, and she needs to find him beacuse it's in trouble. She shows Liz Ten the painting.
On the Maldovarium in 5145, River meets with Dorium to obtain a Time Manipulator, taken from a handsome Time Agent. She offers him a Callisto Pulse, which is necessary to disarm the explosives she hid in his wine.
In the TARDIS, Amy is considering Rory's engagement ring, unable to remember what it is. The Doctor drops down and she quickly hides it, and he takes her to the world's oldest cliff in the universe to read the writing that has been there since the beginning of creation. they emerge and read the words "Hello Sweetie" and a set of coordinates.
The TARDIS arrives in Britain in the Roman time. There is a camp of legionnaires nearby and a soldier approaches, hailing the Doctor as Caesar. He plays along and the legionnaire tells him that Cleopatra will see him now. The Doctor and Amy go to the tent and find River there, posing as Cleopatra. She gives him the Van Gogh painting, which shows the TARDIS exploding.
As the Doctor, Amy, and River ride across the countryside, Amy remembers their earlier conversation. Date and time references were on the TARDIS door sign in the painting, indicating where the Doctor needed to arrive. The title of the painting is The Pandorica Opens
. The Pandorica is a legendary prison built to contain the most feared thing in all the universe. The Doctor insists that it's a fairy tale, but River insists that it relates to the TARDIS exploding. The Doctor figures that the Pandorica is hidden at Stonehenge.
The trio arrives at Stonehenge and the Doctor and River scan for the Pandorica. When Amy notes that River told them about the Pandorica the last time they met, River explains that was a future version of herself. They detect signs of recent energy discharges, and the Doctor concludes that various power blocs would fight for it for what it would contain. They open the rock concealing a passage to the underhenge and go down. They're unaware that nearby, a severed cyberhead lies on the ground... twitching.
In the underhenge, the trio find a massive door. Unbarring it, they open the doors and find a huge stone box: the Pandorica. They also find a severed cyberarm on the ground. As he examines the Pandorica, the Doctor relates the legend of the prisoner within falling out of the sky after being tricked by a good wizard. When Amy comments that it sounds like Pandora's Box, her favorite story, the Doctor suspects it's no coincidence. Something within the Pandorica begins to open it from the inside, and the Doctor wonders if they've met. The Doctor realizes that the stone pillars are broadcasting a message to everyone, everywhere, that the Pandorica is opening. While the Doctor wonders why he hasn't heard it, River wonder what else is coming. River analyzes the signal and nearby space, and discovers that there are at least 10,000 ships in orbit, representing many of the warlike races of the galaxy.
The Doctor and the others run outside as the ships assemble overhead. River warns that there's no way to fight and advises him to run. Instead, the Doctor gets an idea and suggests that they use the Romans. River rides back to the camp only to discover that the commander, Marcello, has arrived and realizes she's not Cleopatra. She tries to explain that that he's as insignificant to the newcomers as barbarians are to him. When that fails, she demonstrates an energy pistol and says that there is a man who will need Mmm's help. A volunteer emerges from the shadows and offers his services.
In the underhenge, Amy asks what the Pandorica has to do with the TARDIS explosion. The Doctor tells her to worry about one problem at a time. Amy shows him the engagement ring and wonders why the Doctor has it. He claims it's the memory of a friend he lost, but Amy says that it reminds her of something. The Doctor hints that something can be remembered, but Amy abruptly dismisses it. The Doctor returns to the topic of why he took her, and he says that he did have a reason. He points out that her house was too large and had too many rooms, and that her life doesn't make any sense.
The cyberarm opens fire and the Doctor and Amy duck for cover. He explains that it is looking for fresh meat and asks Amy to draw its fire while he gets behind it. When she does, the Doctor manages to grab and disable it. As he works, he warns her to stay back... and the cyberhead grabs her, using extended tentacles. The arm releases an electrical charge, knocking the Doctor unconscious. The cyberhead ejects its previous occupant's skull and tries to attach itself to Amy's head. She throws it to the ground but it fires a anesthetic dart and informs her that she will be assimilated. The Cyberman body arrives and attaches its head, and then approaches her. As she tries to maintain consciousness, Amy tries to fend the Cyberman off. she falls back through a door and locks it, Suddenly a sword blade plunges through the door. It opens, revealing the impaled Cyberman. The volunteer Roman is standing there: Rory, who knows her by name. As Amy passes out, Rory catches her in his arms.
Rory's fellow soldiers arrive with the Doctor, who tries to determine why the Cybermen would have imprisoned one of their own. The Doctor is so busy thinking that it takes him a minute to realize that Rory is alive and well, despite the fact he was erased from history by the time crack. Rory admits everything is fuzzy, and wonders if Amy missed him. before the Doctor can explain, the ground shakes. The Pandorica begins to open in its final phase. Hundreds of ships assemble overhead and River warns the Doctor that theyr'e surrounded. He tells her that he needs her to bring the TARDIS and she rides off. Meanwhile, the Doctor ponders what could possibly be locked within the Pandorica that is so valuable.
As the ships assemble overhead, the Doctor steps out onto Stonehenge and uses a loudspeaker to address them. He remidns them of all the times that he's defeated them, and advises each one to let someone else go first. The alien ships fly away to regroup.
River enters the TARDIS and dematerializes it, but it reacts badly.
Rory wonders what the Doctor has planned. Amy arrives and has no idea who Rory is because he was wiped from history. Once she goes, the Doctor explains that Rory never existed.
The TARDIS plummets through the Time Vortex as River wonders is wrong.
The Doctor explains that there is a huge explosion that will cause cracks in time, He has no idea how Rory got there, and Rory explains that he remembers dying, and then he was a Roman soldier with a new life, and everything of his first life was a dream. The Doctor tosses him the engagement ring and tells him to go for Amy even though there's no explanation.
River manages to stabilize the TARDIS in June 26, 2010 on Earth. Once she leaves the TARDIS, a voice says, "Silence will fall," and a familiar crack appears across the TARDIS monitor screen. River discovers she's at a house in Leadworth and finds patterns burned into the lawn. Going inside, she realizes that it's Amy's house and discovers books about Roman Britain and Pandora's Box.
Rory goes to see Amy, who still doesn't know who he is. However, she starts to cry.
River calls the Doctor and tells him to listen.
Amy starts sobbing but she says that she's happy.
River explains that the Romans at the camp are the exact same ones in Amy's picture book. He figures something is using Amy's memories and went to her house to take a snapshot of Amy's memories. They both wonder who the Romans are, and why they're helping them, and the Doctor realizes that they have perfect memories of who they claim to be... until they're activated. River finds a photograph of Rory and Amy at a costume party... with Rory wearing a Centurion costume.
Amy strokes Rory's face and he says that she has to believe.
River realizes that someone has constructed a trap using Amy's memories, to build a scenario the Doctor would accept. The TARDIS engines start overloading and River warns that something is controlling it. When she tells him the date, he realizes that she has to leave. When River can't get free, he tells her to shut down the TARDIS but she is unable to. The voice speaks again, saying "Silence will fall."
Rory insists that he came back for her, and she has to remember.
In the underhenge, a high-pitched signal activates. All of the legionnaires freeze and then come back to life... including Rory.
The Doctor tells River to shut down the TARDIS and prevent the explosion, but she warns that it's not safe. The Pandorica doors open as the legionnaires march. Rory tries to resist, insisting that he is Rory.
The TARDIS lands and the Doctor tells her to leave, forcing an automatic shutdown. She runs to the doors only to discover that they're sealed. The Doctor looks up and discovers that the legionnaires have revealed their gun-hands, exposing themselves as Autons.
On the surface, Rory tells Amy that he's a thing and she has to run. She remembers him and insists that he's not going anywhere again.
The TARDIS explodes around River, who tries to pry the doors open.
The Autons take the Doctor captive and the Daleks teleport down.
Amy asks Rory to show her the ring. Fighting for self-control, he brings it out.
The Daleks announce that the Doctor has been scanned for his limitations and capacities. The Cybermen, the Jadoon, the Sontarans, and many more teleport down and announce that the Pandorica is ready... for the Doctor. Inside the Pandorica is a containment harness.
Amy insists that Rory is himself, and will be staying. His gun-hand opens and he shoots her.
The Autons take the Doctor to the Pandorica, while the assembled aliens look on.
Amy collapses to the ground, dead.
River tries to reroute power to open the doors.
The Doctor is placed in the containment harness and wonders how they can be working together. They explain that all reality is threatened and he thinks they've come to him for help. Instead, they explain that all projections show the Doctor will destroy the universe. A scenario was devised from Amy's memories to trap the Doctor and bring him to the Pandorica. Since only the Doctor can pilot the TARDIS, they believe that imprisoning him will keep it from exploding. The Doctor insists that he's the only one who can stop it, but they seal the Pandorica.
River gets the TARDIS doors open only to discover a solid stone wall. She says, "Sorry, my love.
Rory holds the dead Amy in his arm while across the universe, all of the stars go out.