A classic third Doctor novelization! UNIT is called in when an important diplomat is attacked in his own home - by a man who vanishes into thin air! Traveling forward in time, the Doctor and Jo find themselves trapped in a future world where humans are slaves and the Daleks have already invaded. Using their ape-like servants, the Ogrons, to maintain order, the Daleks are now the masters of Earth. As the Doctor desperately works to discover what has happened to put history off-track, the Daleks plan a time-jump attack on the 20th-century.