A century ago, Agatha Christie's Hercule Poirot energized his little gray cells and discovered whodunit in "The Mysterious Affair at Styles." It was Christie's debut novel and the first of many to feature her dapper Belgian sleuth with the egg-shaped head. That head housed a singular brain, which again and again allowed Poirot to outperform the police, outfox criminals and solve the most complex and fiendish murders.

In 1975, a year before Christie's death, Poirot took his final bow in "Curtain." However, in recent years he has enjoyed a new lease on life, thanks to the Christie estate's inspired decision to commission fresh Poirot cases from the English author and self-proclaimed "Agatha superfan" Sophie Hannah. "The Killings at Kingfisher Hill" marks Hannah's fourth Poirot outing. Once again she ably channels Christie and delivers a deftly plotted, pleasingly intricate and thrillingly executed mystery.

It begins one cold day in February 1931. "That was when the strangeness started," writes the book's narrator and Poirot's sidekick, Inspector Edward Catchpool. The two men board a luxury coach to travel from London to the private country estate of Kingfisher Hill.

Richard Devonport has summoned Poirot to solve his brother's murder and save Richard's fiancée, Helen, from the gallows. But Helen is adamant that she is the killer and has already confessed to the crime. To complicate matters further, Richard's sister Daisy has also declared herself guilty.

Poirot's assignment comes with the curious stipulation that he is to conduct his investigation without mentioning the true nature of his visit to the other members of the household.

But before the coach departs for Kingfisher Hill, an agitated woman with an "unfinished face" announces to Poirot that she has received a terrifying warning: If she sits in a specific seat, she will be murdered. The first leg of the journey passes without incident but after a stop at an inn the passenger manifest goes missing, a bloodstained garment appears, and a lady vanishes. Are these bizarre happenings related to Poirot's inquiry? And can he catch a killer and prove Helen's innocence before the date of her hanging?

Hannah keeps her readers on their toes through numerous twists and turns, right up until the trademark drawing-room denouement. We sift clues, wondering at the significance of a solitaire ruby engagement ring, a board game called Peepers, a book called "Midnight Gathering," and a gate porter. We weigh suspects, who include a tyrannical paterfamilias, an irascible aunt, and a beautiful woman with a "diamond-bright voice."

"What it comes to in the end is that everybody, perhaps, is capable of murder," says the narrator of Christie's 1949 novel "Crooked House." The same applies here, particularly when a second corpse turns up.

"Poirot is the finest detective at work anywhere in the world," remarks Catchpool at one point. It is good to see that he is still at work, in Hannah's more than capable hands.

Malcolm Forbes has written for the Times Literary Supplement, the Economist and the New Republic. He lives in Edinburgh, Scotland.

The Killings at Kingfisher Hill
By: Sophie Hannah.
Publisher: William Morrow, 288 pages, $27.99.