"X Marks the Spot" was the final episode actually scripted by series creator Sherwood Schwartz himself, in collaboration with son Elroy, which begins in unusual fashion at the Pentagon in Washington, preparing to launch a nuclear warhead called Operation Powderkeg, its destination in the South Pacific bound for Gilligan's Island, ready to destroy everything within a 100 mile radius. Fortunately the actual explosive is removed due to a technical fault, but the castaways aren't made aware of that, surprised that it fails to detonate upon landing in the lagoon. The Professor deduces that only Gilligan can crawl inside the warhead to defuse the bomb, once he identifies the wires that need disconnected. Schwartz again miraculously mines laughs out of a serious situation, no easy task for a premise that CBS executives still despised. Good old fashioned slapstick with the Skipper and Gilligan both hit in the face by a pie, as earnestly as if they were Laurel and Hardy.