"The Mob Doctor" episode "Legacy" opens with a flashback to Grace's childhood, during a happy weekend when her dad wasn't drinking. He took her to the zoo, made her pancakes, and played with her. Sadly, his good period didn't last.
At the hospital, this week's cases include a heart patient in need of a transplant. The patient, Sara, is prepped and ready for surgery when she develops a sudden fever. Grace is unable to give Sara the heart they had ready, as hospital policy prevents patients who may have septic fever from receiving a healthy heart. After a workup, it is revealed that Sara isn't septic. She is cleared for surgery, but she now has to wait for another heart to become available.
Constantine requests that Grace visits a patient in prison. His name is Eddie, and it turns out he is Sara's dad. Eddie and Constantine were cellmates back in the day, and now Eddie has a favor to ask. Eddie wants Grace to kill him and give his heart to his sick daughter. Grace refuses. She took an oath to do no harm: Killing a man to take his heart would get her medical license revoked.
Meanwhile, Grace's doctor boyfriend has a mysterious case. His patient has an intestinal blockage, but no one can determine the cause. IBS, Crohn's Disease, and diverticulitis have all been ruled out, and so Grace's boyfriend says they will need to operate on the teenage boy.
Elsewhere, the intestinal blockage patient has a younger brother who is also experiencing strange ailments. His leg is bothering him, but when the doctors ask the boy to take off his shoe, the boy's entire foot twists upon itself, and the boy screams in agony. The muscle spasms are severe, but the cause is unknown even after multiple tests are performed.
Grace's boyfriend works with Olivia on the case of the brothers, and they discover that the two boys might have a genetic cause for their ailments, which both relate to twisting spasms in the body. Testing confirms a genetic mutation that could be responsible.
Meanwhile, Constantine sends his newest associate Nate around the neighborhood to offload some video poker machines and reestablish his role in the community as an enforcer. Some business owners want to forget their ties to Constantine, while others seem glad to have Constantine back in town. However, Nate has a run-in with a member of the Chicago PD and gets badly beaten up when he tries to shake down a bar owner. In a twist, it is revealed that the Chicago PD officer actually works for Constantine, and his attack on Nate was just a way of testing Nate's loyalty.
Constantine orders a sniper to take out Eddie, and Grace uses that opportunity to prep his organs for transplant. However, when Sara learns that her new heart will come from her father's body, she rejects the surgery. She would rather die than have a piece of her estranged father inside of her for the rest of her life. Grace knocks her out with extra painkillers, and then lies to her superiors about getting verbal consent from Sara. After surgery, Sara is furious but doesn't tell the hospital that Grace lied.
- Disease & Medical Conditions