Harper's Young People, February 24, 1880 An Illustrated Weekly

In a sleepy French coastal town, two spirited boys—Pierre, the wiry local lad, and Jack, his sturdy English‑born friend—spend their days hauling nets and dreaming of adventure. When a scientific society offers a hefty prize for anyone who can trace the mysterious underground river known as the Larve, the duo sees a chance to turn their modest lives into something extraordinary.

Eager to prove themselves, they set out at night in their modest boat, hoping the darkness will hide them from danger and lend a touch of romance to their quest. A sudden storm erupts, testing their courage and seamanship as towering waves threaten to swamp their vessel. The boys must rely on quick thinking, daring, and the guidance of Pierre’s aging fisherman father to survive the tempest and keep their hope of uncovering the hidden waterway alive.