It is April 1945 when U-boat U-2072 heads out of Hamburg for the last time. In its hold, the torpedoes have been replaced by gold and Nazi loot. The destination is Argentina. On board, ruthless Kapitanleutnant Falk Friedrich has brought his fiancée, Kristin Dassler.
The U-boat is attacked by American torpedo bombers off the Bahamas and sunk. Kristin finds herself in a lifeboat with three others including Bern Munkelt, the man she is to spend the rest of her life with. They are rescued by Danardo Rolle and taken to Little Toe Cay a remote island where Kristin's adventures continue.
Danardo knows of a secret U-base on Middle Toe Cay, an adjacent island, that they visit to find U-549 sealed inside with another cargo of gold. After an attempt to catch Kristin and her companions, the crew of U-549 fly out in a German flying boat just before the Royal Air Force arrives. Kristin, Bern and Danardo remove the gold and some art masterpieces from U-549 and hide it in the labyrinth of caves beneath the island. Kristin draws a map of the route in and later copies it from her native German into English. For safety, she posts the original to herself, care of a Florida post office. However, the English translation has errors in it and the original map goes missing for fifty years.
However, the local police intervene and Friedrich is deported from the Bahamas. Kristin and Bern deposit the gold they have with them, a small proportion of the total amount, into a Bahamas bank account, buy forged papers and prepare to emigrate Florida. Falk Friedrich who also escaped the sinking of U-2072 turns up and his ruthless personality is revealed..
Almost two decades slip by.
Friedrich traces Kristin in Florida and kidnaps Debbie, her teenage daughter, in an attempt to get Kristin to reveal where the gold is hidden. Debbie and her friend, Wilt Emmet are held in a tidal cave on Middle Toe Cay. With the spring tides growing higher every day, the pair will drown unless Kristin reveals the position of the gold within the week. So begins a race against time to find Debbie and Wilt. Danardo, with an expert knowledge of the cave system, helps.
In the new millennium Kristin's granddaughter, Christine Munkelt, receives a lost letter in the mail. It is the original map that is discovered after an old post office was demolished. Kristin, now an elderly lady, compares the two maps, finds the errors she originally made in the translation to English and corrects them. Christine sets off to find the long lost gold.
Intermingled with the adventure covering three generations, are the romances between Kristin and Bern, Debbie and Wilt and Christine and Cameron, a young man she meets on the journey to find the gold. Also the story tells of Golden U Marina, the company Kristin and Bern start in Fort Lauderdale and build into a large enterprise over the next five decades of their lives.