The Trip.

A married man has an affair with a much younger colleague. The two decide to celebrate her anniversary on a secluded island in the Danube Delta. From the moment they arrive, everything goes from bad to worse, without any logical explanation. After discovering that the only person who could take them back home is dead, the desperation to escape the island becomes uncontrollable, leading them to do unimaginable things to each other. Only one of them will leave the island in the end, answering the question that has haunted them since their arrival: Who else has been with them on the island all this time?