Purgatory Chasm is one of those stories about the well-meaning sort of guy who has a knack for winding up in ugly situations. In this case, Conway Sax is a former race car driver who threw his career away on booze, but found help in an AA group called the Barnburners. Conway learned some stuff, somewhere, and he uses that stuff to help any Barnburner who asks. The one asking is Tander Phigg, who would like his car back from a Mercedes mechanic along with $3500 he claims he's owed. Surprise! People start dying.
That being said, Ulfelder crams a lot into just under 300 pages. There are drugs, guys who were in the French Foreign Legion, guys described as looking like lounge lizards, crazy redneck survivalist types. Conway's girlfriend is also a Barnburner, his buddy lost a limb serving in the military.
Ulfelder is really into family drama. Conway's alcoholic father appears as a homeless bum, Conway and Charlene each have teenage kids who are deeply in love. There are characters with kids they didn't know they had, kids who left the country for years only to return with families. There's child molestation, unwitting incest, more alcoholism. The further into the book you get, the nastier it gets.
At a certain point, I thought it reminded me a bit of the T. Jefferson Parker books I read maybe a decade ago, where any plot twist you could conceive of - usually involving someone's parentage - could happen. But Purgatory Chasm isn't nearly that unpredictable. I was able to see pretty much every twist or surprise reveal, whereas books like Laguna Heat left me flabbergasted at the convolutions the author came up with. Which isn't a bad thing, by itself. I stopped reading T. Jefferson Parker because I got sick of the out of left field crap. The downside is that because they're fairly obvious ahead of time, the plot seems thin, and all that other crazy stuff starts to look like window dressing to hide that fact.