"There's nothing to do here but to keep from disappearing." Lt. Commander Morton Seaview is carrying a new missile, and Nelson has orders to deliver it to its launch site at all costs. Unfortunately, the missile malfunctions, and Nelson can't get into the sealed silo to fix it. Soon, the crew starts to disappear, and bizarre phenomena plague the ones who remain. * This episode features a brief uncredited cameo by Richard Basehart's son, John, as a young crewman in the Missile Room: the Admiral asks him, "What's your name, son?" (thetvdb.com)