The series stars Matt Smith as the eleventh Doctor. The Doctor is an alien Time Lord who travels through time and space in his TARDIS. It also stars Karen Gillan and Arthur Darvill as his companions, newlyweds Amy Pond and Rory Williams. Alex Kingston also returns as River Song, a woman from the Doctor's future who is revealed throughout the series to be Amy and Rory's daughter. The series continues some of the storylines from the fifth series.