Series 4

Ex Polaris submarine captain Edward Holt is in command of HMS Hero currently on duty in the Hong Kong area.

An executive jet flying a routine trip to Singapore issues a mayday call and is forced to ditch at sea. Captain Holt and the crew of HMS Hero are ordered to investigate.

One of the islands in the vicinity of Hong Kong now has a large oil field, to which the UK would like favorable concessions. To show the British presence, HMS Hero drops anchor in the port and Captain Holt and his crew practice their diplomacy ashore.

Hero is asked to help the Hong Kong police catch wanted murderer Victor Chelten, a former businessman with mental issues who has escaped by boat.

Whilst watching a naval helicopter exercise HMS Hero rescue a Chinese girl from the water. When they return to Hong Kong it is with the assistance of the police that the mystery starts to unravel.

HMS Hero is docked at Eddowes Island, which is about to be handed over from British rule. The locals are welcoming to the Hero's crew, but they're opposed to the handover, and some are resorting to violence. The Hero's crew are asked to help keep the locals in order, which worries Captain Holt, and Lt Napier in particular.

HMS Hero is now on its way back from Hong Kong. As they move closer to Portsmouth harbour the ship's crew prepares for shore leave.

HMS Hero's overworked pilot accidentally flies into the RNR manned HMS Rillington's firing exercise. He spends the next exercise on HMS Rillington while their irritating Lt Mannering inflicts his bragging on Hero. An emergency then occurs.

Having returned from an exercise the HMS Hero crew are needled about the state of their ship by Captain Calder.

The new officer on HMS Hero is a Special Duties commission: in this case, a former Petty Officer. He attacks his new role perhaps too vigorously and this is not helped by being unable to mix well and so learn from the other officers.

Whilst observing a Russian ship, HMS Hero finds and takes aboard an experimental unexploded mine.

As HMS Hero continues to steam home to Portsmouth, the RAF drop a post package for the crew. For Able Seaman Blane this starts unsettling rumours as to the state of his marriage back in his home village.

After an uprising - in which five British citizens have died - Hero and Bulwark are deployed to Dubarr in order to pick up evacuees. Captain Holt's girlfriend, journalist Zoe Carter, is one of the people trapped in the country.