Books like Case of the Disappearing Duchess by Nancy Springer

When eccentric millionaire Samuel W. Westing dies, sixteen heirs race through riddles, blizzards, burglaries and bombs to solve his will and claim a mysterious $10 million inheritance.

Hercule Poirot boards Le Train Bleu for a quiet trip to the Riviera, only to investigate the murder of American heiress Ruth Kettering in her luxury compartment.

Ten‑year‑olds Petra and Calder tackle a mysterious art heist when a Vermeer vanishes, using their unique skills to solve a cross‑continental scandal.

A gripping teen mystery where London is terrorized by murders echoing Jack the Ripper, and a group of school kids take on the challenge of tracking down the killer while confronting chilling supernatural forces.

Lady Miranda rises from poverty to marry a widowed duke, navigating family scheming and unfulfilled expectations in Regency England.

In a Regency England setting, Allegra Morgan, daughter of England’s wealthiest man, marries duke Quinton Hunter under a pact that love will be forbidden, yet their forbidden attraction and the looming threat of the French Revolution test their vows and fortunes.

Anne Danvers becomes Duchess of Waverly, only to discover her husband, the Duke, vanished on their wedding night and is a disputed heir. As their forbidden love deepens, a dark secret and a blackmailer threaten to destroy their future.

A heartbreakingly handsome, infuriatingly arrogant gentleman makes a dangerous woman his wife.

When cousin Salim vanishes from the London Eye, siblings Ted and Kat team up to unravel the mystery, chasing clues across London while Ted’s unique mind offers the unexpected key to solving the disappearance.

"Where have you been, Miss Windham?" The Duke of Strathrannock spoke so harshly that Fiona was startled. "I have...." she began feebly. "Do not bother to lie!" he said furiously. "Have you had enough lovemaking tonight or are you looking for more?" To her astonishment, he pulled her roughly into his arms, and kissed her with lips hard and possessive. "I must struggle. I must free myself." Fiona thought. But suddenly, she felt a warm, thrilling sensation rise up through her body. It was incredible--like a rapture that rippled through her like the waves of the sea. She felt it envelop her until her mouth was soft beneath his, her body no longer tense in his arms. It was then the Duke raised his head. "Damn you!" he cried hoarsely. Then, as violently as he had taken her, he left, walking quickly down the corridor, his kilt swinging behind him.

When Lucinda becomes the new wife of the Duke of Avonlea, a former runaway bride, she appears to find security—until a rival’s threat forces her to flee, threatening to end the Duke’s reputation. The Duke vows to reclaim his “unwilling” bride and restore his honor.