The Deep Six Affair - S4.E14

In London U.N.C.L.E. agent Brian Morton (Peter Bromilow) is planning on getting married much to Waverly's disapproval. Solo and Illya help Morton on his current mission, stopping THRUSH agent Commader Kroler (Alfred Ryder) from stealing the plans for a new supersubmarine. Waverly tries to dissuade Laura Adams (Diana Van Der Vlis), Morton's fiancee, but to no avail. Morton and Laura are then kidnapped by Kroler, and Kroler threatens to kill Laura if Morton does not obtain the sub for him.