S4, E18: The half-eaten body of a doctor is found in the tiger cage at the zoo following a hospital charity event, and Booth and Brennan determine the death was no accident. The team soon identifies the victim as Dr. Andrew Welton, and Cam reveals that she was engaged to Welton and lived with him 10 years ago. Though she is devastated by the loss, she nonetheless joins in the investigation to help find Dr. Welton’s killer for the sake of his 16-year-old daughter who Cam once helped raise, potentially creating a life-changing situation for Cam. The team pieces together Dr. Welton’s final evening as they question the suspects, including Brandon Casey, whom Sweets and Angela must hypnotize in order to jog his memory about what he saw the night of the gala. Meanwhile, lust is in the air at the Jeffersonian and Angela is obsessed by sexual thoughts as she tries to maintain her self-imposed celibacy.