Thura Film / Director: Aake Sandgren

One day while scuba diving off their grandfather's boat, teenage brothers Christian (Robert Hansen) and Ask (Ralf J. Hollander) discover the infamous German submarine U-461, which sank off the Danish coast at the end of the Second World War with its load of top secret scientific experiments. As the boys discover the dark secrets that have survived inside the submarine they get in the way of modern treasure hunters with motives of their own.

All interior ship sets including all wrecked submarine sets were built at DDF Studios in Copenhagen on various types of water tanks.