"Who's that woman?" Samson asked, sitting in the chair the doctor motioned to. "Who?" "In the hall, like she's possessed." "Marietta? She has Tourette's, a very severe case. It makes her tic like that. She has an overpowering impulse to mimic whatever she sees." Lavell lifted a stubby finger and rubbed his eyebrow. "A colleague of mine, smart guy, wrote a case study of her. Whether the individual Marietta truly exists or if the impulses, so all-consuming, make her just a phantasmagoria of a person."