A heavily pregnant Amy is home in Leadworth and married to Rory when she gets a visit from the Doctor who has been away for five years. As they show him around, he falls asleep and wakes up back on the TARDIS with Amy and Rory. When they all wake up in Leadworth again though, they realise one scenario is real and one is a dream, but which one?
The mysterious Dream Lord materialises and tells the Doctor that they will be in danger in both worlds and must allow themselves to die in the one they think is a dream in order to wake up in reality.
In Leadworth, the elderly residents are turning children into dust and it emerges that an alien race known as the Eknodines have taken over their bodies. Meanwhile, in the Tardis, the trio may freeze to death as they have only 14 minutes before they crash into a star that is burning cold.
The Dream Lord places the onus on Amy to choose. When Rory is turned into dust in Leadworth, she believes this is the dream world and that she has to die to see him again. When they all wake up on the TARDIS, the Dream Lord tells them they have won and disappears, but the Doctor now believes both worlds were a dream and blows up the TARDIS.
They awake on a working TARDIS and Doctor reveals that the Dream Lord was a result of psychic pollen which fed on dark elements inside people.