Cover blurb:

"Mysterious humans from 22nd-century Earth 'time-jump' back into the 20th century so as to assassinate a high-ranking diplomat on whom the peace of the world depends.

Doctor Who, Jo Grant and the Brigadier are soon called in to investigate. Jo is accidentally transported forward to the 22nd century; the Doctor follows, eventually to be captured by his oldest and deadliest enemy — the Daleks!

Having submitted the Doctor to the fearful Mind Analysis Machine, the Daleks plan a 'time-jump' attack on Earth in the 20th century...!"