Illya goes to U.N.C.L.E.'s secret island training academy, the Survival School, to help Jules Cutter (Richard Beymer) find a THRUSH infiltrator who has assassinated a trainee. Suspicion focuses on three trainees Melisa Hargrove (Susan Odin), John Saimes (Chris Robinson), and Harry Williams (Charles McGraw), and Illya must find out who is the real double agent.