Goosebumps Slappy World Attack of the Jack!

Violet and Shawn Packer have been sent out to sea. Well, more like sent out to visit their Uncle Jim, who lives near the ocean. He's an old admiral who sleeps in an old lighthouse with his cat. But Violet and her brother realise quickly that the lighthouse is full of Admiral Jim's secrets. Like a door he tells them never to open. A treasure chest that is full of the strangest items. And Captain Jack, who is absolutely not what he seems. Will Violet and Shawn survive the open water and make it back home where they belong?