Cassie's Pittsburgh ER has been deluged by young patients who have overdosed on a new drug, FX. After Cassie discovers that the source of the FX on the streets is her own hospital, her best friend is killed, and Cassie's life is threatened. She is forced to place her trust in Detective Mickey Drake.
Drake's irascible charm eventually penetrates the barriers Cassie has built around herself, and their relationship progresses from professional to passionate. After Cassie discovers the truth behind the thefts, she and Drake must confront a killer. In the end, their only weapons are their newfound love and the courage that it gives them.