Doctor Who (1963) - 3x16 - The Feast of Steven (7)

When the Doctor and his friends arrive on Earth, they find that Chen has already denounced them as traitors, and Vyon is shot and killed by his own sister, Sara Kingdom. Sara eventually discovers the truth for herself, and helps the Doctor and Steven to recover the TARDIS and escape. However, the Daleks then pursue them through Time, and are joined by the Doctor and Steven's old enemy, the Meddling Monk – who realises that he's in over his head and switches sides depending upon who seems to be on top. After an encounter in ancient Egypt, the Doctor strands the Monk on an ice planet, but the Daleks get away with the taranium core, and the Doctor uses the navigational unit from the Monk's TARDIS to pursue them back to Kembel. There, the Daleks exterminate Mavic Chen, but the Doctor manages to activate the Time Destructor. Sara ages to death before she can reach the safety of the TARDIS, but the Doctor and Steven escape while the Dalek force on Kembel crumbles to dust.