'THOSE WHO CONTROL THE TARDIS HAVE INTERFERED WITH TOO MANY OF OUR PLANS. THEY ARE TO BE DESTROYED. IF NECESSARY, THE ASSASSINATION GROUP WILL PURSUE THEM THROUGH ALL ETERNITY. EXTERMINATE THEM!'
The Doctor, Barbara and Ian had faced - and narrowly defeated - the Daleks twice before. They had known that there was always the possibility that the Daleks would win. But the reaches of time and space had always seemed so safe - there was always the chance that if they were being overwhelmed, they could flee.
But now the Daleks can track them through all of time and space. They try to shake off their attackers by making a series of random landings, but this is a chase to the death...