British ex-pat Dr. Cal Lightman (Tim Roth) is a body language expert, specialising in micro-expressions and founder his applied psychology contracting company The Lightman Group, which assists in a variety of law enforcement investigations.
Previously a member of British Intelligence, having apparently served in Northern Ireland and the Yugoslav Wars, Lightman started researching micro-expressions as a young boy after the death of his mother.
He shares custody of a teenage daughter, Emily Lightman (Hayley McFarland), from a former marriage and supports English football team West Ham United.