Institutionalized (Demon Squad Book 10) by Marquitz, Tim

Blood on his hands, bridges burnt, ancient entities unleashed, the world falling into chaos, and it’s all Frank “Triggaltheron” Trigg’s fault. So what does he do?He joins the enemy, of course.Out of options, Frank surrenders to the DSI in hopes of working out a deal that will save DRAC and end the supernatural rebellion he instigated. As it turns out, the punishment for his crimes is the absolute worst thing he could imagine.They offer him a job.Now tasked to hunt down the former head of the DSI, Frank is caught up in a chess match that just might determine the fate of the universe.Who really needs a happy ending, anyway?