Demonprice, or, Doom of the Penultimate Husband — Phoebe Matthews

As though demons aren't pesky enough, now a con man from Hell is tricking Nathan out of his soul, one fifth at a time. In an attempt to save Nathan, Elaine and Charley wind up in Hell's vestibule. By the author of the EPPIE award winning urban fantasy Mudflat novel, here is another series set in contemporary Seattle, on the other side of town.