The Master, in the guise of Professor Thascalos, has constructed at the Newton Institute in Wootton a device known as TOMTIT - Transmission Of Matter Through Interstitial Time - to gain control over Kronos, a creature from outside time. The creature is summoned but proves to be uncontrollable.

Credits

Paul BernardDirector

Jon PertweeThe Doctor

Katy ManningJo Grant

Roger DelgadoThe Master

Nicholas CourtneyBrigadier Lethbridge-Stewart