Tommy's life from early childhood is a blur of sudden flights and hiding under the constant protection of his father, who weaves thrilling tales of pirates, smugglers, and treasure-trove to shield the boy from a mysterious enemy called 'Shadow-of-Fear.' Their wanderings lead them across England, dodging unseen pursuers, until a fateful night in a wayside hut brings a beggar woman named Bite-in-the-Dark into their shelter. A violent struggle ensues, ending in a deadly confrontation and a fiery escape that leaves the past behind but deepens the mystery of the family's relentless flight.
As Tommy grows older and physically stronger, their wanderings frequently return to the Dolphin Inn and the wild, rocky coast nearby. Here, Tommy hones his survival skills, learning tracking, swimming, and knife-fighting from his father, while searching for a hidden underground passage that he suspects connects the shore to the woodland. His chance encounters with smuggler leader Dirk Stormaway lead him deeper into the local underworld of espionage and betrayal.
Tommy's inquisitive nature eventually leads him to discover the secret of Ebb-Tide Cave and the massive rock gates that hide a subterranean cavern. During a clash between smugglers and King's men, Tommy navigates the watery underworld of Drift-Wood Cavern, witnessing the dark consequences of past crimes and the exposure of a treacherous spy. These events weave a tangled web of suspicion around his father, whose true identity and past actions remain veiled in ambiguity.
Seeking a quieter life, the pair eventually move north to Sunset Towers, a haunted mansion on the desolate moors. Here, Tommy forms a complex friendship with Worthing Bright, a disciplined schoolmate drawn to law and order, while continuing his pursuit of the mansion's architectural secrets. The dark history of the house, combined with whispers of an ancient, cursed treasure, begins to weigh heavily on their lives.
In a climactic gathering, the father recounts a detailed, harrowing tale of a doomed expedition on the Spanish Main, the slaughter of priests, a buried treasure of gold and rubies, and the lingering curse that pursues all who touch it. This narrative casts a long shadow over Tommy's understanding of his father's flight and the dark forces that drive it.
Following a dramatic fire and a separation from his father, Tommy finds himself under the care of Captain Field and his spirited daughter Jenny at Sunset Towers. In this new phase, Tommy navigates youthful rivalries and deep attachments, all while being hunted by authorities and haunted by the lingering presence of his father's enemies. The story balances a boyish coming-of-age adventure with psychological tension and an unyielding quest for truth.
The narrative culminates in a convergence of past and present perils, where Tommy is dramatically rescued from a terrifying fate by Dirk Stormaway at the Smugglers' Gate. As the story pauses on the shore of Ebb-Tide Cave on the first of May, Tommy awaits his father's return, poised between the lingering curse of the treasure and the hope of a reunion.
