The whole city of San Francisco wants a cop-killer caught. Over at Giants stadium Hugh Patterson’s jolly mug fills the Jumbotron: 30K reward and the good will of the city, the tabloids, the cops.

Patterson was a good cop. No ordinary beat-walker. Loved his uniform, helping old ladies and handing out stickers to kids. He was a believer, a Giants fan. He was a man of the people until one of the people put a bullet in his head, then five more for good measure.

Patterson’s partner, Vince Alvarez, a cop in golden handcuffs, doing his time until retirement. Bust the baddies and get home to his wife, his high school sweet heart. Doesn’t give a fig about more than that. She’s his reason for being and maybe some day they’ll have kids.

Shooting at 24^th and Capp, San Francisco’s Mission District, good cop goes down. Bad cop’s got a shoddy story, looking for someone to pin it on.

Meet brothers Oscar and Ramon Flores. Bad blood between them. Real bad. Ramon passing down painful memories of their absentee father by abusing Oscar, 15.

Oscar’s a good kid, sees an opportunity to even up with his brother. Ramon’s been bad to Oscar—BAD—and making Oscar for the bloody cop-drop solves more than a few problems: money for his hard-working moms; Ramon on ice for a cop-kill rap; a perpetually grateful city.

Tom Pitts doesn’t mince words in Knuckleball, fleshing out a broad swath of characters in a few short strokes. We track closest with Alvarez. Where was he when Patterson went down? Wouldn’t do to be a few blocks away seeking privacy while placing a jealous call to his wife. No answer. No answer. What’s she up to she can’t reach for the phone on the first two tries?

So IA’s got Alvarez’ balls in a vice, and Alvarez’s got a squirrely story about a phantom perp. Could be anyone. Conveniently vague. Vince’s shabby story works in Oscar’s favor. All we need is another eye-witness to corroborate, pick Ramon out of a line-up.

In baseball the man on the mound tosses down a knuckleball to throw off the hitter. Twist him up, tie him in knots, swatting at air. In crime fiction, Knuckleball serves the same purpose, has the same impact: spare, effective, a plot about a diversion that works. Watch Pitts weave baseball and crime and self-preservation and the guys who get busted and dusted deserve it even if they didn’t do the crime.