The Doctor is convinced the Ice Warriors are trying to sabotage the conference but his attempts to prove it see him accused of sacrilege.
Quest roles:
Murphy Grumbar(Dalek Operator), Sonny Caldinez(Sskel), David Troughton(Peladon), Geoffrey Toone(Hepesh), Stuart Fell(Roga), Alan Bennion(Azaxyr), Terry Bale(Voice of Arcturus (voice)), Nick Hobbs(Wirrn Operator), Ysanne Churchman(Spider (voice)), Gordon Stothard(Grun)