Izzy was singing on the beach near the water edge when she meets a young sea unicorn that quickly bond with her offering a golden shell so she could summon her when ever she may need her.Izzy gives the sea unicorn she named Cornica the sea shell necklaces as a token of their friendship.Izzy wanted to introduce Cornica to the rest of her crew,While sets off to find her friends.Cornica is captured by Captain Hook in order to find the legendary treasure of the magical sea unicorn hidden deep beneath the depth of the Never Sea.Once Izzy return to the beach with her friends she was shocked to see that Cornica was no where in sight and didn't come when she use the shell.Jake suggest that they ask the mermaids if they knew where to find Cornica.Once at Mermaid Lagoon Izzy ask the mermaids have they seen Cornica.Queen Coralie and a few of her subjects didn't believe the young pirates since sea unicorns are merely a legend in mermaid folklore and set off to take care other matter else where.However Stormy was the only mermaid to believe her young friends and agreed to assist her friends locate Cornica near the Coral Tunnels and they thanked stormy for coming with them. Back at the Jolly Roger Hook attempts to ride Cornica to the treasure, which the seahorse quickly bucks off the greedy captain.Not letting the beast stand in his way for treasure Hook ties Cornica up on top the Squidailus (a squid like submarine),Hook threatens to take away Cornica's necklace if she doesn't lead him to the treasure.Fortunately Jake and his crew accompanied by Stormy quickly follow Hook and his crew beneath the wave in their mini subs.Once Hook reach Coral Tunnel he cause a cave in block the path. Jake and his friends manage to by pass the cave in to pursue Hook and his crew following the glow of Izzy's shell.Just in time to prevent Hook and his crew from escaping with the treasure which was almost their undoing causing one of the large golden statues to collapses only for Izzy to rescue Hook and his crew with her pixie dust.Smee , Sharky and Bones thank Izzy for rescuing them. Izzy ask Hook for the necklace which Hook quickly part with no longer needing when he could swipe the rest of the sea unicorn treasure. Cornica inform Izzy to use the golden shell to call Cornica's larger sea-unicorn comrades forcing Hook and his crew to flee empty handed. Jake and his crew soon return to Pirate Island to place their gold doubloon they collect on today adventure into the Team Treasure Chest.Meanwhile Hook was sitting atop the Squidailus sulking yet another plan has for riches has slip from his grasp.In order to cheer Hook up Sharky and Bones show the captain a unicorn like frog they found and suggest they follow to find it s toady treasure,Hook was not amused by the gesture believing the frog was a fake tossing the amphibian before bellowing to crew to head back to the Jolly Roger, no sooner then Hook and his crew leave the frog when it hops off exposing a treasure hidden on the beach.