About this book:

After the death of her uncle Eamon, archivist Ava Calder returns to the remote Breakwater Cove to claim his lighthouse. She soon discovers that Eamon was the guardian of a "Tidal Archive," a submerged vault containing a dangerous 1940s chemical weapon and evidence of a massive political conspiracy. Ava is thrust into a high-stakes race against Damien Crowe, a ruthless developer, and a shadowy preservationist known as "The Watchman," both of whom seek the "Lighthouse Key"—a complex brass instrument required to unlock the vault.

Teaming up with ex-Coast Guard officer Jonah Reyes and local historian Maeve O’Connell, Ava decipher’s Eamon’s cryptic tide-based ciphers to locate the Key hidden within the lighthouse's structure. As the group evades professional fixers and navigates a web of historical betrayals involving Maeve’s own family, they discover that the vault’s contents are chemically unstable. Ava must not only unlock the secrets of the past to expose a decades-old corruption but also engineer a way to neutralize a potential ecological disaster before the vault is breached.

During a climactic confrontation at the "Sea Dragon’s Teeth" rock formation during a spring tide, Ava successfully uses the Key to stabilize the chemical threat and retrieve a final logbook that clears the names of "The Innocent"—local men who were framed for the original conspiracy. Though the physical Key is sacrificed to permanently seal the vault, the truth is brought to light, leading to the downfall of the corrupt local power structure and the retirement of the clandestine "Watchman" network.

In the aftermath, Ava establishes the Eamon Calder Coastal Preservation Trust, transforming the lighthouse from a site of secrets into a legitimate institution for coastal stewardship. Having reconciled with the past and found a partner in Jonah, Ava accepts her role as the new Keeper, ensuring that the lighthouse remains a beacon of transparency and a protector of the sea’s memory for generations to come.