If ever a guy was “in cahoots,” it was St. Paul Police Chief Tom Brown. He was in cahoots with Al Karpis, Ma Barker and sons. In cahoots with John Dillinger and his gang. In cahoots with the shady characters who ran St. Paul’s underworld from saloons and city offices.

Brown’s role in some of gangland’s storied heists and kidnappings is the subject of St. Paul author Tim Mahoney’s latest book, “Secret Partners: Big Tom Brown and the Barker Gang.”

“Police corruption in St. Paul didn’t start with Tom Brown,” Mahoney quickly points out. Other city officials set up the system. But you get the impression that Brown perfected it.

Mahoney takes us beyond the familiar tales of St. Paul’s gangland culture in the 1920s and ’30s and into the civic culture that abetted it. How Brown used his role with the city’s kidnap investigation squad to steer Ed Bremer into the grasp of his kidnappers. How Brown made sure the Barker gang had enough time to flee their hideout with the Hamm kidnapping loot. How Brown just happened to be one of the cops who gunned down gangster Homer Van Meter near University and Marion. Double-dealing doesn’t begin to describe this guy.

It’s a wild romp through a wild city at a time when famous names such as Bremer were not as well-respected as they are today. Where even the seemingly good guys weren’t all that good. Where St. Paul Daily News editors decried corruption in print and dealt with dirty cops in private.

Mahoney digs deep for details, and the narrative suffers for it in places. Readers can get lost in the many names and nicknames and hideouts of gangsters and molls and the changing cast of mayors and police chiefs. I wish I’d had a spreadsheet to keep them all straight.

Still, you can’t go far wrong with a story about corrupt cops and the gangsters they helped with killings, kidnappings and escapes. Mahoney does a fine job of putting Brown at the scene of the crime and showing us how he got away time after time. Along the way, it’s fun to spot familiar landmarks: the old Schmidt Brewery, the Lincoln Court apartments and the federal courthouse now called Landmark Center, where the Bremer kidnappers were brought to justice.

As for Tom Brown’s date with justice, well, his partners in crime could only wish things had worked out as well for them.

Maureen McCarthy is a team leader at the Star Tribune.