Struggling with his dual identity, failed comedian Arthur Fleck meets the love of his life, Harley Quinn, while incarcerated at Arkham State Hospital.

During the 1980s, a failed stand-up comedian is driven insane and turns to a life of crime and chaos in Gotham City while becoming an infamous psychopathic crime figure.

When he is betrayed by a trusted friend, Mathayus must marshal all his strength and cunning to outwit a formidable opponent who will stop at nothing to unlock a supreme ancient power.