In the heart of Laos, a father-son team of professional divers embarks on a perilous mission to locate the wreckage of the La Grandiere, a French gunboat that sank in the Mekong River in 1910. Carrying a cargo of priceless Buddhist artifacts, the ship's disappearance has been shrouded in mystery for a century, with local legends suggesting a curse haunts those who seek to recover the lost treasure. Battling treacherous currents, zero visibility, and the constant threat of submerged hazards, the divers must rely on their expertise and cutting-edge technology to navigate the river's dangerous depths and uncover the truth behind the ship's final, tragic voyage.