The Pirate Submarine

In Short

Set in the years following the Great War, this story centers on a desperate pair of business partners who transform an old salvage submarine, the Alerte, into a pirate vessel. As they prey upon merchant ships, the narrative tracks their internal power struggles, the capture of unwilling "guests," and a relentless cat-and-mouse game with the Royal Navy. It remains a classic of the genre because it captures the technical fascination of early submarine warfare while grounding its plot in the timeless, rugged landscape of the Cornish coast.

The Story

The story begins in the shipbreaking yard of Polkyll, where partners Tom Trevorrick and Paul Pengelly face financial ruin. Trevorrick, a charismatic and iron-willed man with a background in the Royal Navy, proposes a radical solution: they will refit an old submarine, the R 81, for salvage work—and then use it to hunt merchant shipping as pirates. Under the alias "Captain Cain," Trevorrick establishes absolute command, relegating the resentful Pengelly to a secondary role. They escape Falmouth Harbor, disguised as a harmless salvage vessel, and quickly begin their campaign of plunder.

The crew’s first act of violence involves attacking the Cap Hoorn, a move that forces two innocent yachting enthusiasts, Gerald Broadmayne and Rollo Vyse, to become permanent, unwilling guests aboard the submarine. As the Alerte moves through the Channel, tensions rise. The crew, initially enamored by the prospect of easy wealth, soon find themselves living in cramped, dangerous conditions, governed by Cain’s volatile leadership. Pengelly, meanwhile, grows increasingly envious of Cain’s command and begins to sow seeds of dissent among the men.

The climax approaches when the Alerte attempts to hijack the Bronx City, a vessel carrying a massive cargo of gold. This error in judgment—attacking an American ship—brings the full weight of the authorities down upon them. A decoy ship, the Canvey, is dispatched by the Royal Navy to hunt the pirates, forcing the Alerte to flee into a narrow estuary. Sensing the trap, the crew mutinies against Cain, installing the inept Pengelly as captain.

The transition is disastrous; the Bronx City escapes, and the Alerte is cornered. In a final, dramatic reversal, the crew turns back to Cain, realizing he is the only one capable of navigating them out of the predicament. Cain regains command, but the situation is beyond saving. He orders the crew to abandon ship, having rigged the submarine to scuttle. As the Canvey closes in, the pirates are captured and brought to trial. Pengelly is sentenced to penal servitude, but Cain’s ultimate fate remains a mystery. The submarine is destroyed, and the story concludes with the lingering, unanswered question of whether the resourceful, mercurial captain managed to slip away into the depths, leaving his pursuers with nothing but the wreckage of his ambitions.

How It Unfolds

The voyage begins Trevorrick and Pengelly transform the R 81 into the pirate craft Alerte under the guise of an Admiralty salvage operation. They recruit a crew of desperate men, promising them a fortune in hidden treasure and plundered cargo.

The first haul After successfully capturing the Cap Hoorn, the pirates take two young men prisoner to maintain the secrecy of their operation. This act of kidnapping sets the stage for the moral conflicts and internal friction that define the rest of their voyage.

The rendezvous The ship travels from the Cornish coast to the dangerous waters off Brittany, constantly dodging naval patrols and searching for supplies. Pengelly’s growing dissatisfaction with his position as second-in-command creates a palpable danger for everyone on board.

A stern chase After attacking the wrong target, the pirates are hunted by a specialized decoy ship commanded by the British Navy. The resulting pursuit traps the submarine in a river, where the crew ultimately realizes they have lost the advantage.

The fate of the pirate submarine Cain regains control just long enough to ensure his crew's safety and the destruction of the ship. The story ends with the pirates imprisoned and the legend of the submarine relegated to a mystery of the deep.

The People

Captain Cain (Tom Trevorrick) is the story’s driving force, a man of immense physical presence and naval expertise. He treats piracy as a disciplined, almost professional pursuit, yet he is prone to sudden shifts in temperament. He ends the story as an enigma, having successfully commanded the loyalty of his crew even while leading them to ruin.

Paul Pengelly is the antithesis of his partner, characterized by his sallow features and deep-seated insecurity. He desires the power Cain holds but lacks the charisma to command, eventually becoming a pathetic figure who resorts to mutiny out of spite. His story concludes with legal disgrace.

Gerald Broadmayne and Rollo Vyse are the "unwilling guests" whose presence provides the reader with a tether to normality. Through their eyes, we see the brutality of the pirate life. They remain resilient, eventually serving as key witnesses for the Admiralty, though they maintain a strange, lingering respect for Cain’s capabilities.

In Its Own Voice

"That's done it! Scrap brass has fallen another thirty shillings a ton, Pengelly. The slump has knocked the bottom out of the market. We're in the soup."

Trevorrick delivers this ultimatum to his partner, setting the desperate financial tone that initiates the plot.

"To-morrow, Tom Trevorrick ceases to exist as such. Henceforward I am Captain Cain--'every man's hand against mine,' you know."

Trevorrick sheds his former identity to fully embrace the persona of a pirate captain.

What It's Really About

At its heart, this is a study of command and the fragility of order. The book explores the tension between legal authority and the raw, individualistic desire for self-determination. It asks whether a person’s character is defined by the uniform they wear or the actions they take when the laws of society are stripped away. There is a secondary preoccupation with the transition from the old ways of sail to the clinical, mechanical reality of submarine warfare, suggesting that the "pirate" of the modern age is a relic trying to survive in an increasingly surveyed and interconnected world.

Why Read It Today

Readers who enjoy classic, high-stakes nautical adventure will find this a compelling read. It possesses a distinct, rhythmic quality—the prose is crisp and moves with the efficiency of a well-oiled engine. The period detail, particularly the descriptions of early submarine technology and the local color of the Cornish coastline, is vivid and immersive.

However, modern readers should be aware that the book reflects the attitudes and linguistic quirks of the early 20th century. The characters express a rigid social hierarchy, and the casual, often brusque treatment of the crew and the "prisoners" reflects the period's standard approach to adventure storytelling. The pacing is relentless, eschewing deep psychological interiority for a focus on action and external conflict. It is a story that captures a specific moment in time—both in its literary style and its obsession with the "new" technology of the undersea vessel. Those who appreciate the tension of a Boys' Own adventure, tempered by a darker, more cynical edge, will find much to enjoy here. It leaves the reader with a lingering sense of mystery, perfectly capturing the feeling of a legend that refuses to be fully pinned down.