John hopes to become the first dry human to prove that wet Mermaids exist. Mike's worried, because whilst the UK braces itself for a winter onslaught of hurricane force winds, John's latest water-based quest for the truth looks like it'll end up with both of them in Davy Jones' Locker. A trip to see a local storyteller leaves John believing he's found some 'solid mermaidy fact' but as storm winds build, a visit to the national library of Wales provides the opposite of evidence and leaves John stormy with anger. John's not going to give up on his Mermaid obsession. Mike's attempts to wash away the theory with help from a marine biologist backfires spectacularly and The Unexplainers find themselves heading out on the high seas using the mystical and magical floating powers of something called "a boat".