With the Doctor out of action, it is up to Polly, Ben and Barclay to stop Cutler using the Z-Bomb and devastating half the world.
Quest roles:
William Hartnell(The Doctor), Anneke Wills(Polly), Michael Craze(Ben), Robert Beatty(General Cutler), Dudley Jones(Dyson), David Dodimead(Barclay), Steve Plytas(Wigner), Christopher Matthews(Radar Technician), Ellen Cullen(Geneva Technician), Christopher Dunham(R/T Technician), Callen Angelo(Terry Cutler)