THRUSH agent Anton Korbel (Ken Murray) guards THRUSH's fifty-million dollar treasury in a vault beneath his casino, and Solo and Illya recruit a naive girl from Minneapolis, Susan Callaway (Marlyn Mason), and shady safecracker Marcel Rudoph (Dan O'Herlihy) to break in and destroy the cash.

Solo and Illya protect a young Himalayan prince (Michel Petit) and his nurse (Susan Seaforth) from THRUSH agents who want to kidnap him one of whom turns out to be his bodyguard.

Solo uses the former girlfriend (Kathryn Hays) of 2 brothers, Joseph and Max Van Schreetan (Gerald Mohr, Lloyd Bochner), to thwart their plan to control the diamond market, while at the same time THRUSH agent Corio (Alfred Ryder) tries to steal their cache of gems.

Solo and Illya travel to the Riveria, where they search for a serum that supposedly provides great strength and even brings the dead back to life. There they meet Madame Streigau (Marian Moses), who is actually Dr. Egret of THRUSH, as well as Lucia Nazarone (Danica d'Hondt) and her bevy of beautiful blonde helpers. With the help of teacher Lavina Brown (Kipp Hamilton), they trick Mazarone into thinking they have the serum also, and become the targets of her "superwomen".

U.N.C.L.E. and Thrush agents compete to gain possession of a mind-reading device created by a magician who has been murdered by Thrush.

Illya goes to find Thrush's vaporizing machine, but is captured by Sophie, the headstrong daughter of the local tribal chief, Sulador. in New York Solo convinces retiring THRUSH agent David Lewin that THRUSH intends to kill him, and elicits his help. Lewin and Solo are taken to the base in the desert, just as Illya leads the band of nomads, whose confidence he has gained, in an attack on the base.