Kate Blake (Nina Dobrev) is happily married to Danny Williams (Patrick Dempsey). They have been a couple since they met at college and are now both surgeons at Saint Claire's General Hospital in Seattle. Everything is perfect but when she meets the new principal consultant, Nathan Stark (Robert Downey Jr.), her whole world turns upside down. His sudden arrival causes some serious problems in Kate's life with dangerous consequences. What is she going to do? Is her marriage strong enough to deal with these difficulties? Who is she going to choose? Kate is torn between two men...