The echo maker

"On a winter night on a remote Nebraska road, twenty-seven-year-old Mark Schluter has a near-fatal car accident. His older sister, Karin, returns reluctantly to their hometown to nurse Mark back from a traumatic head injury. But when Mark emerges from a coma, he believes that this woman -- who looks, acts, and sounds just like his sister -- is really an imposter. When Karin contacts the famous cognitive neurologist Gerald Weber for help, he diagn...