 In the three months since the end of " The Impossible Astronaut " , the Doctor , Amy , Rory and River Song have been attempting to track the Silence , an alien race who cannot be remembered after they are encountered . Ex @-@ FBI agent Canton Delaware , under the ruse of capturing them as criminals , helps to reunite the group inside a special prison at Area 51 containing the TARDIS . Though they do not yet know the name or motive for the aliens , the Doctor 's allies have discovered they exist across the entire planet , and have the ability to place post @-@ hypnotic suggestions in humans they encounter . The Doctor plants a communication device called a <unk> in each of the group 's hands to record audio of meetings with the Silence . As they travel to Kennedy Space Center shortly before the launch of Apollo 11 , Amy tells the Doctor she was mistaken and is not pregnant as she previously had claimed . 
