"Tell me the rules," Marcus said, because angels didn't show up in alleys and debts always demanded payment.

The story follows Joe Flood (Bautista), a veteran contract killer who operates by a strict moral code: he only targets criminals. After meeting and falling for Maize (Boutella), a dancer, Joe is diagnosed with a terminal, rare brain disease. Wanting to spare Maize the pain of watching him deteriorate, he authorizes a hit on himself through his rival, Marianna (Pom Klementieff).