Investigator Lucas Davenport discovers that the Cold War never ended for a gang of Soviet-era spies living in rural Minnesota. They've remained hidden for years, until the murder of a Russian seaman at a Duluth freight terminal. Despite the unlikely premise, Hidden Prey is one of the strongest in Sandford's ''Prey'' series. The threat of a Red menace that hides in plain sight is eerily suspenseful. Sandford introduces some intriguing supporting characters, including alluring Russian agent Nadya Kalin and communist-in-training killer Carl Walther, a fresh-faced teen who arranges murder around choir practice. ''I can't do it tomorrow night,'' Carl tells his leftist grandfather, a creepy 92-year-old puppet master who's alternately cold-blooded and compassionate. ''We're singing.'' Sandford makes a good case for Communist revival, at least in hard-boiled thrillers.