A case of mistaken identity leads the Doctor (Peter Capaldi) to an encounter with wife River Song (Alex Kingston) on Christmas Day, 5343. Despite River not recognizing her "sweetie" in his current incarnation, the pair is soon off on a thrilling adventure involving a valuable diamond, a few more of River's spouses, and a hulking robot that wants the Doctor's head...literally. Matt Lucas, Greg Davies also star. 60 min. Widescreen; Soundtrack: English.