S1·E29 The Odd Man Affair

Retired U.N.C.L.E. agent Albert Sully (Martin Balsam) is brought back to impersonate a crime syndicate leader, and insists on leaving Solo and Illya behind and running the operation himself. He reunites with wartime fellow agent and old flame Bryn Watson (Barbara Shelly) and tracks down a secret crime conference, with the exasperated Solo and Illya trying to keep him from being killed in the process.