Nate Heller, president and sole employee of Chicago's A-1 Detective Agency (Stolen Away, etc.), takes on six real-life unsolved mysteries in this collection of stories set in the 30's and 40's. As Ed Gorman points out in a brief introduction, pulpmeister Collins freely mixes fact and fiction, with uneven results. The two shortest stories, ""The Strawberry Teardrop"" and ""Scrap,"" are little more than historical reconstructions, though a post-Chicago Eliot Ness enlivens one of them. In ""Private Consultation,"" ""House Calls,"" and (especially) ""Marble Mildred,"" Collins is able to mix true crime, seedy-jokey atmosphere, and hard-boiled detection more successfully; and the title novella, asking whether the Chicago's most notorious serial killer (""stop me before I kill again"") is responsible for the kidnapping and murder of a little girl, is worth the price of admission by itself--a tough, nervously sentimental tale that ranks with Collins's best. A collection most notable for the way it bridges the gap between the straightforward twists of Black Mask and the current slanted ironies of Paretsky and Estleman.