Evan, an overworked software engineer, has recently reconciled with his dying mother who, unbeknownst to him, fell under the spell of a murderous demon when Evan was young. Raised in foster care, Evan has emerged as a lonely, drug-addicted adult, whose only solace lies in his flute music. When he and his boss, Bob, cut corners on the software testing of a new military flight control system, the consequences are devastating, and summon the return of the old demon, who offers Evan a devilish deal to save himself -- and the girl he loves.