A story about a cat-and-mouse game, Liar centers on career con artist Roy Courtnay (McKellen) who can’t resist one last score when he meets well-to-do widow Betty McLeish (Mirren) online. As the woman opens her home and life to him, the man is surprised to find himself caring about her, turning what should be a cut-and-dry swindle into a treacherous tightrope walk as not all is what is seems.