After the TARDIS materialises, The Doctor exits the space ship and finds that Amy Pond is pregnant and is married to Rory Williams and they are living at Leadworth. The Doctor has allegedly been away for five years. Rory has a pony tail hairstyle. Rory is now a doctor and not a nurse which had always dreamt of being.
After the Doctor gets re-acquainted with his friends, they hear tweeting noises and fall asleep. The three companions wake up onboard the TARDIS where they discover they all had the same dream or as the Doctor calls his, a nightmare.
A mysterious man appears and reveals that his name is the Dreamlord as he appears in their dreams. The Dreamlord tells them that one of their dreams is real, either the one in Leadworth or the one in the TARDIS. They can only die in one reality but not both. The Dreamlord is played by guest star Toby Jones.
The crisis in Leadworth is that there are Eknodine who have taken over the old people and want to conquer the world. The Eknodine are inspired by Alien where when one of the old people opens their mouth, an eye pokes out. The Eknodine sprays green gas which turns people to dust. In alien, the creatures eat and spit acid but they don't do that in Doctor Who.
In the other dream, the TARDIS is heading to a Coldstar and is making the TARDIS extremely cold. There is nothing in reality called a Coldstar, the closest to reality is a Y-Dwarf which can be colder than the human body according to Space.
The Dreamlord separates Amy from the others and gives her the choice of what reality should be real. It is a test over which kind of life that Amy wants. The Dreamlord calls it Amy's Choice. When Amy returns to Leadworth, she is unable to prevent Rory from being turned to dust. Amy says that Leadworth is fake reality and she then with the Doctor commits suicide by driving a camper van into a house killing them.
The three friends wake up on the TARDIS where the DreamLord congratulates them on working out which is real. The Dreamlord turns on the TARDIS and begins to warm the place up. The Doctor realises that they are still in a dream and causes the TARDIS to head into the coldstar killing them.
The three friends wake up again on the TARDIS where the Doctor reveals that he realised it had all been a dream because the Dreamlord has no power in the real world. Both realities had been a dream. The Doctor says it had been influenced by Psychic pollen which they had picked up on a previous planetary visit.
Amy confesses that her heart is for Rory after Rory discovers that Amy had committed suicide out of love for him and they confess their love for one another.