The Hammersley saves sailors from a sinking ship, only to learn they are diamond smugglers who will kill to save their cargo. Swain is kidnapped by smugglers and left trapped in their sinking ship. Will Buffer rescue him before the ship sinks? Mike is reprimanded by Navy brass over his obsession with the Bright Island mystery.

As the decommissioning of the HMAS Hammersley draws near, the crew risks life and ship to hunt down a rogue terrorist boat and retrieve its cargo of bio-toxins. In ordering the sinking of the rogue ship, Mike makes the most difficult decision of his career.