Grace is stunned to learn Constantine has an estranged son when the son makes a surprise visit to Chicago. Turns out the son is deep in debt to a drug cartel and doesn't have the money to pay them back. Now the cartel wants him dead. Constantine offers to clear the son's debt, but in order to do that, he needs help from Al Trapani. But first Trapani needs some help of his own: his girlfriend is sick and needs a doctor. Constantine assigns Grace to take care of Trapani's girlfriend and in the process she discovers a secret that could jeopardize both their lives if it ever comes out. Meanwhile, Olivia and Dr. White deal with the medical mystery of a patient who died in the emergency room, only to come back to life. The episode ends with the drug cartel, upset that Constantine is interfering with their business, making a major move against Constantine - and everyone he knows.