In 1965, in Northern Spain, a dam will be built to bring progress to the location of Desbaria and the town of Marienbad is near to be completely flooded. Two boys, Teo and Luis, cross the security boundary to play in the evacuated town and Teo listen to voices in the abandoned church. They find a group of strange people chained in the watered basement, Teo releases their leader Mordecai Salas and is killed by him. Forty years later, in the celebration of the fortieth anniversary of Debaria Dam, the teenager Antonio vanishes in the lake while swimming with his girlfriend Susana and their friend Clara Borgia. The police divers, with the support of the outsider cameraman journalist Dan Quarry that is filming the submerged Marienbad to write a matter about the town, try unsuccessfully to find the body. When eerie things happen in the spot, Dan and the local journalist and daughter of the builder of the dam Teresa Borgia disclose dark secrets about Marienbad...