The Seaview is en route to rendezvous with the fleet when Sharkey reports a missle fuel leak. Crane and Morton believe it's worth returing to port to repair, however Nelson knows how to handle it. Taking a small breathing device with him, the Admiral locks himself in the compartment in question to effect repairs. However, he drops a wrench, the circuts blow and Nelson is knocked out. When he comes to, he's gripped by paranoia which worsens with each passing minute. Trusting no one, Nelson loses his grip on reality, arresting Doc, fighting with Sharkey and finally launching a nuclear missle at the fleet! (thetvdb.com)