Journalist Halber introduces readers to the unusual world of web sleuthing: in this case, crowdsourcing the task of comparing the thousands of reports of missing persons to those of unidentified remains in the hopes of finding a match and bringing closure to families searching for lost loved ones. The author paints a colorful picture of armchair investigators pursuing their first "solves" amid the conflicting motivations of their peers and of various law enforcement agencies—the infighting of the online missing-persons communities is effectively juxtaposed with the red tape and politics of real-world departments and policymakers. Perhaps unintentionally, Halber's decision to intermingle various cases and sprinkle the result with a large cast of characters evokes what one imagines is the same feeling a web sleuth gets hopping from one missing-persons report to another, looking for connections. The occasional bizarre similes don't overly detract from an intriguing invitation to help mitigate a "silent mass disaster" that few are even aware has happened. VERDICT Puzzle fans, true crime aficionados, and heavy users of Internet forums will appreciate Halber's shout-out to aspiring consulting detectives.—Ricardo Laskaris, York Univ. Lib., Toronto