2/4 The High Priest of Sacrifice, Tlotoxl, begins to doubt Barbara's claim to be Yetaxa.
1/4 The TARDIS lands inside an Aztec temple in 15th Century Mexico and becomes sealed off.
6/6 The Doctor solves the murder mystery and finds the final missing key.
5/6 Arriving in Millennius, Ian is put on trial for murder. The Doctor takes his case.
4/6 In a snowy wasteland, Vasor, an unscrupulous trapper, imprisons the travellers.