Irish crime writer Dervla McTiernan burst onto the scene with 2018’s claustrophobic, clever The Ruin, and she has kept to an annual release schedule since. “The Murder Rule” is a diabolically clever combination of courtroom drama, procedural mystery, and revenge thriller, and it hangs on a humdinger of a hook: what if someone joins the Innocence Project, dedicated to freeing longstanding wrongly convicted murderers, with the aim of vengeance not freedom (I’m not offering a spoiler here, the novel’s blurb says just that). Law student Hannah blackmails herself onto the University of Virginia’s classic team of crusaders and the author gradually reveals the hidden story of her motives. McTiernan is superb at unraveling the plot, which explores two old crimes in forensic detail, and the evidence-gathering plotlines are plotted well. Hannah is an engaging protagonist and all the other characters mesh in well. Toward the end, courtroom scenes introduce an almost Perry-Mason-ish atmosphere, I suspect most readers will not be able to put the book down. My only final quibble was a denouement, after clever twists, that felt emotionally untrue, but I do very much recommend The Murder Rule.