Uncle Pete’s plane is missing, again! It’s been shot down by evil wildlife hunters and has sunk deep into the cold Arctic sea. That means Uncle Pete and TM will have to go and find it, fix it and bring it home. But how? By Squirrel Submarine, of course! But wait! The crew of the Squirrel Submarine are having a well-earned rest at the NutLand Holiday Park after their last adventure, which means Uncle Pete and TM will have to drive the submarine themselves. How hard can it be? Pretty hard, as it turns out! Uncle Pete and TM get themselves into all kinds of crazy underwater adventures and dilemmas as they search the deep for their plane. Meanwhile, the lost plane has been discovered at the bottom of the ocean by a clever and curious octopus who decides to fix it and use it to explore his world, helping other sea creatures along the way.