Admiral Nelson wanders the Seaview and finds it abandoned except for Captain Crain and Chief Sharkey. He has no memory of what happened before or what the strange sounds over the intercom mean. Capt. Crane is also trying to kill him.

Strange sounds and events begin to be reported on board the sub. While still coming to grips with the crews edginess, the Seaview encounters a strange 17th century warship that fires on the sub.