The series follows the employees of I.M.P (Immediate Murder Professionals), an imp-run assassination company in Hell, on their many different jobs. The members of I.M.P include Blitzo (pronounced "Blitz"), the boss of the venture, along with weapons specialist Moxxie, powerhouse Millie, and receptionist hellhound Loona. With the help of an ancient book obtained from Stolas, a Goetial demon of Hell, they access the human world to complete their tasks on order from demons in Hell.