Trama

Glomgold tries again to stop Scrooge from being declared the richest duck in the world, this time using a stolen submarine.

Scrooge still has to transport his money to the Grand Quiche's location in Macaroon as part of the 'Firefly Fruit contest' between him and Glomgold.

Meanwhile, Scrooge's nephews are amazed to see that Scrooge has gotten into the ice cream business, and built a large factory next to the Money Bin. However, none of the ice cream trucks stop, and armed guards prevent anyone from going in. One evening, they see a fleet of the trucks heading towards the harbor. Trailing along, they find that the trucks are full of money. The whole ice cream factory set-up is further revealed when they meet Scrooge down at the harbor. Scrooge explains that with Glomgold's spies everywhere, trying to stop him, he created this ruse to ship his money to Macaroon, in two large boatloads.

However, Scrooge's joy is short-lived, when it is revealed that the first shipment sank! Scrooge and the boys go to the location, only to find that the Navy have created a perimeter around the sunken ship. Scrooge and his nephews try to sneak onto the ship, where they find no trace of his fortune. Having disobeyed the Navy's request, he is taken aboard an aircraft carrier overseen by Admiral Grimitz. Grimitz explains he has no idea what became of Scrooge's fortune, but Scrooge feels that the Admiral is hiding something from him.

Also aboard the aircraft carrier is Donald Duck. The Admiral asks Donald to accompany Scrooge, who is planning to transport the second half of his fortune. Grimitz reveals to Donald that he thinks that Scrooge's fortune disappeared due to the stealing of a secret sub, by a Navy scientist named Bluebottle. Word is, Bluebottle went rogue and stole the sub, and noone knows where he is. Unknown to Donald, Grimitz plants a homing device on him before he goes to join Scrooge.

Scrooge transports his money on schedule, with Donald and himself in the hold of the ship. Following behind is another of Scrooge's ships, with Mrs Beakley, Webby and the nephews. Suddenly, they are shocked when a giant killer whale appears out of the ocean, and bites down into the money-carrying boat before them.

Scrooge and Donald then find themselves in the belly of the beast, only to find that it's a machine. It is then that Donald accidentally lets slip about this being a secret Navy project, and how it was stolen by Bluebottle. Supposedly, he designed the sub to resemble a whale so that it would be able to maneuver better in the ocean.

Soon, Scrooge and Donald have found the scientist, who is communicating with Glomgold. Apparently, Glomgold's plan is to have Bluebottle hold onto Scrooge's fortune until after the contest in Macaroon. Scrooge and Donald then attempt to overpower Bluebottle, but he soon captures them, intent on shooting them out of the sub. However, before he can, the sub is rocked by a depth charge. Suspecting that one of them holds a homing device, Bluebottle is proven correct when he finds it on Donald. Smashing it, the Navy loses it's signal, but prepares to fight against Bluebottle's sub.

The battle rages for some time, but eventually, the sub is wounded, and sinks into the Marinara Trench. Scrooge manages to save himself, Donald, and Bluebottle by jettisoning his fortune into the trench, causing the sub to rise to the surface.

With Bluebottle under arrest by the Navy, Scrooge then vows to return to the trench to retrieve his fortune, and get it to Macaroon for the contest.