While Harm and Mac investigate a murder aboard a ship at sea, Harm becomes trapped with two others inside the brig; a collision causes many problems, including flooding of the compartment. Harm solves the crime and becomes rescued.

The admiral unexpectedly arrives in Sydney, and the adventure continues. Mic prosecutes the US former petty officer, and Harm defends. Bud sustains an injury, and courtroom fireworks ensue. The JAG gang take the deserter back to the US.