By Paul Katz
Updated June 20, 2007 04:00 AM

You can count on consistency from inept New Jersey bounty hunter Stephanie Plum. As in her prior 12 adventures, she’s still undecided in Lean Mean Thirteen between bad boy Ranger and sometime boyfriend cop Morelli, partnered with a ”former ho” named Lula, and quarry for homicidal maniacs. This time, Plum probes the disappearance of her shady ex-husband while skirting flamethrowers, a ditzy female stalker, and an exploding squirrel. Janet Evanovich boosts this by-the-numbers series with amusing side characters, like an accountant working out of a food court or horndog seniors flirting near the hemorrhoid-cream aisle. B+