Recurring characters and themes may maintain the continuity of a mystery series, but reopening a case solved in a previous book is a high-risk venture. So is taking the hero out of his jurisdictional depth. C.J. Box tries both tricks in BELOW ZERO (Putnam), the ninth novel in this sturdy series with Joe Pickett, a stand-up Wyoming game warden and all-around good guy.

When Joe's teen-age daughter starts getting text messages from someone claiming to be her adopted sister, who died six years earlier in WINTERKILL, Joe drops his normal durites to search for the girl. And as soon as that search turns into a hunt for a a serial killer who goes after people with big carbon footprints ("One society wedding produced 707 tons of carbon into the atmosphere") Joe finds himself working with the FBI on a case of domestic terrorism. When an agent reminds Joe that he's only "one guy in a red shirt in a state pickup," you can understand the author's impulse to give his hero a career boost. But Joe seems happier as a feet-on-the-ground game warden, and it's still his true element.
- Marilyn Stasio