When Eight Bells Toll

British Treasury secret agent Phillip Calvert is sent to investigate the hijacking of five cargo ships in the Irish Sea and traces the Nantesville to the Scottish Highlands and the port town of Torbay. He and his partner Hunslett begin undercover work posing as marine biologists to blend in with the locals. The case is set against a backdrop of suspicion and danger at sea.

Calvert and Hunslett operate undercover as marine biologists while surveying the Torbay area. The local inhabitants appear suspicious and openly hostile to outsiders. Their investigation tightens around Sir Anthony Skouras, a Cypriot shipping magnate whose influence looms over the region.

Calvert makes contact with Sir Anthony Skouras, who sits aboard the luxury yacht Shangri-La anchored off the coast. Skouras becomes the central figure in the piracy investigation, though no proof is yet attached to him. Calvert weighs the possibility that Skouras is the mastermind behind the hijackings.

A Royal Navy helicopter briefing turns deadly when shore forces attack and the pilot is killed. The helicopter crashes onto the rocky shoreline, explodes, and sinks to the bottom of the sea. Calvert manages to escape as the craft goes down.

Calvert returns to his research yacht Firecrest to confront the unsettling developments. Hunslett is missing, and Calvert is surprised by the presence of his boss, Sir Arthur Arnford-Jones, known as 'Uncle Arthur.' The tension suggests internal pressures as they prepare for a renewed pursuit.

As they raise anchor to set sail again, Calvert and the crew discover the dead body of Hunslett tied to the anchor line. The discovery confirms that the piracy operation is deadly and personal. The team steels themselves for a direct clash with the pirates.

Skouras's wife, Charlotte, emerges from the sea claiming she escaped his yacht after being beaten. Calvert is both attracted to and wary of her, sensing she holds dangerous knowledge. Her appearance threads a complex entanglement into the investigation.

A pirate speedboat approaches, and Calvert rams it, shoots the occupants, and blows up the vessel in vengeance for Hunslett's death. The act demonstrates his willingness to take decisive, brutal action to halt the pirates. The incident also deepens the mystery surrounding Charlotte.

Calvert recruits the local shark fishermen to counter Skouras's pirates and to help locate the missing bullion ships. The alliance expands their resources for the climactic confrontation. The ocean becomes a battleground where unconventional allies play a key role.

Calvert dives into the bay and eventually locates the Nantesville. He fights and kills a diver he suspects killed Hunslett, closing a personal vendetta as part of the mission. The discovery shifts the focus toward the underground docking operation.

Calvert secretly enters Lord Kirkside's castle and questions the Lord's daughter. He learns that Skouras is innocent and that his real wife is being held hostage with other locals in the castle's dungeons. The truth overturns the initial assumption about the mastermind.

Calvert sneaks into the castle's underground dock where the gold is being offloaded. He uncovers the scale of the operation and the pirates' plan to move the bullion undetected. The underground dock becomes the focal point for the final confrontation.

At midnight (eight bells) the shark fishermen ram the gates of the underground dock with their boat. The pirates are expecting them, having been tipped off by Charlotte via secret radio. A fierce firefight erupts as the intruders press the attack.

The pirates are wiped out in the firefight, and Calvert allows Charlotte to escape with a single bar of gold. The operation closes with the truth about Charlotte's role and the exposure of the hostage situation. Calvert secures the bullion as the immediate crisis ends.