Max and 99 must find a spy onboard a ship, amidst a plethora of suspects.
Parts 1 and 2 are probably my favorite episodes of the entire "Get Smart" series, its has a lot of the ingredients that make the situation hysterical. Nice atmospheric mood, a tramp steamer in perpetual fog, tons of suspects that all make a co-incidental "clip clop" noise and spout suspicious dialog, a cliff-hanger between parts 1 and 2, the first appearance of Agent 44 and on and on. When Smart confronts Captain Groman and asks if one of the ship's crew could possibly be implicated, I still laugh at Groman's denial and insistance that its impossible because "each one was hand-picked from the scum of Europe".
A great mixture of the "serious" spy genre, funny dialog, nice set-up, and free from the over repeated "catch phrases" that got a little old as the years wore on.