According to Blogtor Who, episode four carries the title The Power of Three while episode five is named as Angels Take Manhattan.
The series opens with Steven Moffat's Asylum of the Daleks, is followed by Chris Chibnall's Dinosaurs on a Spaceship and A Town Called Mercy by Toby Whithouse.
Episode 4, The Power of Three, is scripted by Chris Chibnall. The story is the Ponds' penultimate Doctor Who adventure and features UNIT.
Angels Take Manhattan, as the title suggests, sees the return of Moffat's popular creation the Weeping Angels and was partly shot on location in New York. It is heavily tipped to be an emotional story as Amy and Rory say goodbye to the Doctor and depart the TARDIS forever.