Flight attendant Cassandra Bowden wakes in her hotel room hungover from the night before in Dubai with a dead body lying next to her. Afraid to call the police, she continues her morning as if nothing happened. In New York, she is met by FBI agents who question her about her recent layover in Dubai. Still unable to piece the night together, she begins to wonder if she could be the killer.

Harley Quinn has finally broken things off once and for all with the Joker and attempts to make it on her own as the criminal Queenpin of Gotham City.