Bruce Wayne and Harley Quinn don't have much in common, except for Cassie Kendall. Beautiful and whip-smart, she nearly changed the course of Bruce's life when she was his high school sweetheart, and shortly thereafter became Harley's college fling. Now, after a long time away from Gotham, Cassie has returned and immediately has her sights set back on Bruce. But when Harley learns of Cassie's return, she is all too happy (and manic, and unpredictable) to reconnect with her old college girlfriend. As Bruce's and Harley's paths cross, it becomes clear that all is not as it seems with Cassie Kendall...