U.N.C.L.E. agents Napoleon Solo and Illya Kuryakin are sent to retrieve Dr. Kharmusi's latest invention, a death-ray called the thermal prism. In order to break into Dr. Kharmusi's secure vault, U.N.C.L.E. seeks out notorious safe cracker Luther Sebastian who is a fugitive from justice hiding in a country without extradition treaties. In exchange for an international pardon, Luther Sebastian agrees to help U.N.C.L.E. retrieve the thermal prism. Secretly, Luther Sebastian has ambitions of his own regarding the new weapon. He's part of a mystical and religious group called the Third Way, that seeks world-domination and whose members and disciples wear platinum white hair. Solo makes his way to Dr. Kharmusi's fortress, Illya Kuryakin and Luther Sebastian are dropped by parachute into the area and sneak into the fortified compound at night. After a series of unforeseen incidents, crosses, double-crosses and unexpected revelations, the U.N.C.L.E. team leaves with the thermal prism while the fortress is in timer-based self-destruct mode. Victory is elusive however because Luther Sebastian double-crosses U.N.C.L.E. and steals the thermal prism. After regrouping at the U.N.C.L.E. HQ in New York, Solo tries to track Sebastian down through his ex-wife from L.A. Later, Solo adopts the typical look of a Third Way member and infiltrates that organization in the hope of finding Luther Sebastian and the thermal prism. Meanwhile, Kuryakin follows up on a tip-off leading to an abandoned L.A. stage theatre. Solo participates at the high-jacking of a U.S. rocket organized by Sebastian and the Third Way operatives. Eventually, Solo and U.N.C.L.E. discover the secret facility where Sebastian and the Third Way plan to set-up a rocket launch carrying the stolen thermal prism. Launching the thermal prism into orbit the Third Way intends to blackmail countries into paying protection money to avoid destruction. U.N.C.L.E. reinforcements arrive and storm the launch facility. The final battle pits U.N.C.L.E. reinforcements against the Third Way forces.