Mr. Waverly (Leo G. Carroll) gives U.N.C.L.E. agents Solo, Kuryakin, Arsene Coria (Fabrizio Mioni) from Italy, and Namana (Bill Gunn) from Liberia their assignment: they are to take a top secret code to a hidden location. After they leave, Waverly sends another agent, Australian Kitt Kittridge (Donald Harron), to follow them without their knowledge. However, THRUSH has gotten wind of the "August Affair", though the villains know little more than the name of the operation. They send Serena (Senta Berger) to entice Solo to her apartment. After each unsuccessfully tries to find out what the other is after, he is gassed into unconsciousness and a THRUSH agent, surgically altered to look and sound like Solo, takes his place. An attempt is made to kill Kuryakin to minimize the chance of the substitution being detected, but it fails. (thetvdb.com)