En amont du fleuve

Two guys in an old motor-launch, step-brothers Homer and Joe who hardly know each other, putt-putt up a gorgeous river landscape in the wilds of Croatia. Their goal is to find out what happened to their father. What was the real cause of his recent and sudden death? They reach impassable waterfalls and are forced to venture into the interior with backpacks, and finally encounter a wandering and enigmatic Irishman who may know more about their dead father than he admits.