The thirst among publishers for titles to which they can attach the “Agatha Christie” brand remains as unquenchable as ever. To serve that thirst, a writer named Charles Osbourne took the raw material of a play that Christie wrote during her heyday and subjected it to a bit of benign violence; in other words, he novelized it. The result, published in 1998, has a few charms and curiosities, but ultimately it’s devoid of the rich, world-building magic that Christie brought to her prose fiction. Try as Osbourne might to invest this treatment with light ironic touches and other writerly grace notes, he succeeds mainly in revealing the creaky, old-fashioned stagecraft that undergirds the original work. In a bid to “open up” the play, he launches his novel with a scene that features sleuth-hero Hercule Poirot in his Mayfair flat. Even so, most of the action here takes place in a single setting—the library of Sir Claud Amory, the victim of the piece. Stock characters, such as Sir Claud’s debt-ridden son and the son’s mysterious foreign-born wife, flit in and out of the room, uttering cliché-laced speeches that move the plot forward across an all-too-visible three-act structure. The murder puzzle hinges on several well-deployed clues (one of which, unfortunately, involves a bit of outdated household terminology), and Osbourne does capture some of the antic flair that marked Christie’s writing at its best. All the same, he fails to close the gap that yawns wide between a well-made play and a well-turned novel.