Derek is tasked with performing a risky surgical procedure in order to remove a spinal tumor from a patient. He and Meredith discuss the problem and potential solutions. During the discussion, Derek draws a diagram of the spine that illustrates the issue the patient is facing. Derek faces a dilemma: if he cuts the cord, he will kill the tumor, but the patient will lose function in both of his legs. Derek tries to find a way to cure the tumor without cutting the cord.