Maybe the book is called 'The Mystery of the Vanishing Book Title' cause it sure as heck vanished from your memory! Seriously though, give us more to work with or we're just shooting in the dark here.

I'm digging into my reading list cause this sounds so familiar. Are you by any chance thinking of the book Shutter Island by Dennis Lehane? It's got that stormy lighthouse vibe, though I'm not sure it's the one because I don't think it's considered modern Agatha Christie style. It was also adapted into a movie. Definitely gripping though.

Wow, a lighthouse and stormy cover, huh? That narrows it down to like, every other thriller out there. Good luck with that one lol... but, check out The Death of Mrs. Westaway by Ruth Ware or maybe some of the atmospheric stuff by Simone St. James? Half of the genre has a small town and someone ends up dead. More details might prevent a wild goose chase.

Lighthouses on covers always catch my eye! The Lighthouse Witches by C.J. Cooke is creepy with magic and witches and stuff but it’s not part of a series. No boat that I remember either. Could THAT be it?

Let me help you out. There's a chance you're talking about The Au Pair by Emma Rous? It fits the bill: a modern mystery, stormy vibes, and there's indeed a lighthouse on some editions' covers. No boat, though, but the protagonist revisits her old home in a coastal area where a lot of secrets start unraveling. It's part of a series too.

first time replying, so hope I'm doing this right lol. Your description reminds me of something I've seen at my library. Maybe check out authors like Charlotte Link or Elly Griffiths? They both have creepy coastal town vibes going on in their books.

idk if it's the one you're thinking of but there's a book called Dark House by Helen Phifer. It's about a detective who moved to a small town. There's a few books following the same character, it's pretty chill inducing. might be what ur looking for?

Ohh, this sounds super familiar! Is it The Lighthouse Keeper by Cynthia Ellingsen? It's not a series though, but the cover and plot sound like what you're describing. If it's not that one, check out her other books maybe?