The colony world of New Pasithea was peaceful for many years. But strange electric pulses started to be detected in its forests... and then they started to get stronger... and then people lost their memories...

The Doctor and Leela land in a community in turmoil, doomed to insanity by the mysterious 'Abeyance' unless the TARDIS crew can save them.

But with reports of monsters being seen in the locality, this may prove harder than expected.

Can they rescue the minds of the colonists? Or will they forget what they have to do...