While Martin continues to struggle with his blood phobia, a mermaid washes ashore in Port Wenn to the amazement of everyone in town. Meanwhile, Judith, a well-meaning townsperson (guest star Andrea Martin), creates havoc while on prescribed oxygen, Louisa continues to see Martin's girlfriend Eden for medical guidance and Greg and George's success from the seas urchin boom take its toll on the both of them.

When the Port Wenn pharmacy is robbed, including Louisa's critical time-sensitive medicine, Martin deduces that the culprit desperately needs his help. Meanwhile, Greg and George clash with a rival food truck owner, Sarah tries to bond with Eden, and Martin is on the receiving end of a special brand of Port Wenn affection.