Lure of the Swamp (1957)

Simon Lute ekes out a modest living chartering his skiff to tourists and guiding them through the labyrinthine bayou. When a mysterious stranger asks him to take them deep into the swamp, Simon is curious, particularly when the man requests to make part of the journey alone. After the man's corpse is discovered the following day, Simon learns that the stranger had robbed a bank and that hiding the loot in the inhospitable bayou was the man's objective. But what should Simon do with this newfound knowledge?