Books like The Crooked Staircase by Dean Koontz

Two young lovers, Tommy and Tuppence Beresford, form a private detective agency and are hired to locate a missing woman named Jane Finn, whose disappearance threatens post‑war Britain.

A high‑stakes sea adventure uncovers a deadly piracy conspiracy and the slave trade in Southeast Asia, as Juan Cabrillo and his crew confront a shadowy syndicate threatening international shipping.

Richard Hannay, a bored Londoner who returns from South Africa, is thrust into a high‑stakes espionage chase after a murder tied to an assassination plot, forcing him to flee to Scotland and outwit his pursuers.

Detective Cassie Maddox transfers out of Dublin Murder Squad but is called back to solve a murder that looks almost identical to her past self.

Detective Jane Rizzoli and medical examiner Maura Isles face a desperate hostage crisis when a corpse miraculously revives, kills a guard, and seizes a pregnant Rizzoli. Only Rizzoli can unravel the mystery before the night ends.

Nola Brown, presumed dead after a mysterious plane crash, is revealed alive by former Navy SEAL Jim "Zig" Zigarowski, forcing them to evade a secretive U.S. military conspiracy while uncovering hidden truths.

Matt Hunter, a former criminal, uncovers a shocking truth that puts his freedom and love for Olivia in jeopardy.

Two men on a road trip find themselves chased by a dangerous, mentally unstable killer.

University professor and FBI operative Anne Waverly, haunted by a past tragedy, faces a final mission when she uncovers over a hundred children hidden in the Arizona compound of the cult-like Change movement.

An anesthesiologist accused of malpractice must chase a conspiracy after a tragic childbirth, racing against time to clear his name and uncover the truth.

In newly unified Germany, neo-Nazi groups stir violence while a shadowy force employs cutting‑edge technology to spread hate and destabilize Europe and the United States.

"I very much need to be dead." These are the chilling last words left by a man who had everything to live for but took his own life. In the void that remains stands his widow, FBI agent Jane Hawk, surrounded by questions destined to go unanswered unless she does what all the grief and fury inside her demand: Find the truth, no matter what. People of talent and accomplishment, people seemingly happy and sound of mind, have recently been committing suicide in surprising numbers. A disturbing pattern is beginning to emerge. Jane is determined to give up everything to find out why. And if that means going rogue and becoming America's Most Wanted, then so be it. Those arrayed against her are legion, and devoted to protecting something profoundly important-or terrifying-enough to exterminate any and all in their way. But Jane is as clever as these enemies are cold-blooded, as relentless as they are ruthless. And she is driven by a righteous rage they can never comprehend. Because it is born of love.

FBI agent Jane Hawk, now a fugitive, must protect her five‑year‑old son from relentless enemies that close in on her home, testing her courage, wits, and discipline in a deadly labyrinth of terror.

A journalist’s quest to uncover a secret gospel left by Mary Magdalene leads her through Jerusalem, Paris and the French Pyrenees, confronting ancient prophecy, supernatural protection and deadly conspiracies.