A boy and his gran live in a lighthouse, high on a cliff. The town below them is a pile of houses where fisherfolk live who love tea and are wary of anyone from outside the town. Mythical creatures live in the depths of the sea that swirls below the cliff and supports the fishing boats, protected by the long-lost silver shell. Some of the creatures are friendly and some less so, but the fisherfolk think all of them are threats. The boy and his gran eventually need to intervene to help the fisherfolk understand that just because someone is from somewhere else, that doesn’t make them a bad person.