A Mermaid Isle Romance Books in Order

A Mermaid Isle Romance is one of Cali MacKay's breezier connected worlds, at least on the surface. The early books lean into coastal charm, old feelings, local history, and the kind of small community where everyone knows the inn, the bookstore, and the stories people tell about buried treasure. Mermaid Isle, off the coast of Maine, is the real hook. The setting gives the whole series a warm, slightly quirky identity.

One Sweet Summer starts with a first-love reunion and a fight to protect the Siren Song Inn from a corporate sale. For Love or Treasure adds a bookstore, pirate lore, and a treasure hunt. Those first books show the series at its most classic, seaside romance with history, secrets, and just enough conflict to keep things moving.

Then the tone starts to stretch a little.

A Mermaid Isle Christmas keeps the cozy weather-locked setup, using a blizzard and forced proximity to bring two damaged people together. Sweet Danger pushes further into suspense territory, with biotech secrets, a weaponized virus, and a heroine on the run. Even when the danger rises, though, the series still feels like MacKay. There is always a couple at the center, and the outside threat exists to test whether they can finally choose each other.

That range is part of the appeal. If you want a connected set of romances that starts with coastal charm and treasure-laced local legend, then gradually makes room for heavier suspense, Mermaid Isle is a fun path through MacKay's catalog. Start with One Sweet Summer if you want the island itself to work its magic on you first.