At Adventure Beach, the pups are enjoying themselves with Alex Porter, when as Alex is getting water for the moat for his sand castle, he spots something in the water. Curious, he waves down Mayor Goodway to show her as well. She is impressed by what she and Alex see in the water, but concerned about the noises it is making, Alex goes to tell Ryder. When Ryder is told of the situation, he's confused at first due to the details Alex provided and what he called the creature, but agrees to help the creature out, and summons the pups to the Sea Patrol HQ.
Once there, Ryder assigns Zuma and Chase to help the creature out, and once Chase and Zuma's boats are loaded into the Sea Patroller, the ship sets sail to help the creature out.
Once they find it, it is not long before the green mane that Alex described comes off the creature, causing Zuma to discover is was just seaweed. As the team continue to check the creature out, Ryder has Zuma take a picture of it to send to Cap'n Turbot in the hopes he can identify it.
Once Ryder calls Cap'n Turbot and shows him the photograph of the creature, the Cap'n identifies it as a Narwhal Whale, which are normally found in the arctic, and realizes that the Narwhal must have been separated from its pod, so the Sea Patrol need to help the Narwhal get back to its pod, supported by Alex, Goodway, and everyone on Adventure Beach cheering the Narwhal on.
After the Cap'n records some Narwhal sounds for Chase to use with his boat's megaphone to get the Narwhal's attention, the Sea Patrol manages to lure the Narwhal after them as they head for the arctic, with Zuma staying underwater to keep an eye on the Narwhal from there.
Once in the arctic, with the pups and Ryder having changed into their winter wear, they start looking for the Narwhal's pod, only to run into trouble when a cargo ship appears, honking its horn. Cap'n Turbot contacts Ryder from back in Adventure Beach, where he, Goodway, Alex, and the others on the beach are watching things on a large television screen, and warns Ryder that the Narwhal might get confused due to the ship's horn mixing in with the Narwhal sounds Chase is broadcasting from his boat. Turns out their fears are confirmed, as Zuma watches as the Narwhal swims around in a panic, before skewering its horn into an iceberg, getting it stuck and helpless as the cargo ship steers right towards it. Ryder manages to contact the cargo ship's captain to warn him and his crew that they need to stop their ship, but the captain replies that he will have a hard time setting his engines to Full Speed Astern as it takes some time for a ship like his to slow down or even stop compared to the Sea Patroller. Chase monitors it to see if the ship shows any sign of slowing as it approaches the iceberg and the Narwhal.
To try and help, Ryder puts on his Sea Patrol scuba gear to aid Zuma with pushing the iceberg and the Narwhal out of harm's way. They manage to succeed with getting the Narwhal out of the path of the cargo ship as it manages to slow down and stop, but while Marshall was confident that they would succeed, Rubble was worried they wouldn't.
Now with the Narwhal safe from the cargo ship hitting it, Rubble puts on his own Sea Patrol scuba gear to help break up the iceberg so the Narwhal can get its horn free. Soon after, the Narwhal pod shows up to reunite with their missing member, and the pups, along with everyone on Adventure Beach watching through Ryder's wristwatch Pup-Pad, wish the Narwhal good luck and cheer for him.