"Liar" is a British psychological thriller that tells the story of a forbidden attraction. It leads to serious consequences for a couple, as well as their families and friends. Laura Nelson is a school teacher who has recently broken up with her boyfriend. Andrew Earlham is a surgeon with an impeccable reputation, whose son is in Laura's class. A brief affair between the two young people leads to a crime. Each of them has their own version of what happened that night. It remains to be seen which of the two is telling the truth.