Are you talking about the Crab Man one? I'll admit that I was thrown off the scent, but the formula was still the same. Introduce the water vendor, introduce the captain (he was in the ep. before, but really introduced here), make the captain the obvious suspect and the vendor the real criminal. I was only thrown off because I completely forgot about the vendor while getting worked up over thinking, "They can't really make it the captain. If they do, then I'll never watch this show again..."