Ian Rankin took on the challenge of finishing his mentor’s book. The result is a darkly beautiful novel.

There’s a strong tradition in mystery writing of living writers continuing the work of dead ones. Think, for instance, of Robert B. Parker completing Raymond Chandler’s unfinished final Philip Marlowe novel, “Poodle Springs,” and then, after Parker’s death in 2010, of his own Spenser series being extended by fellow mystery writer Ace Atkins. Other so-called continuation novels have stretched the active careers of Agatha Christie’s Hercule Poirot, thanks to Sophie Hannah, and Dorothy L. Sayers’s Peter Wimsey and Harriet Vane, thanks to Jill Paton Walsh, who died last year. (There’s no word on who will pick up the series, but I hope it’s not James Patterson.)