Pairing two screen legends together for the first time, The Good Liar tells the story of career con artist Roy Courtnay (Ian McKellen) who can hardly believe his luck when he meets well-to-do widow Betty McLeish (Helen Mirren) online. As Betty opens her home and life to him, Roy is surprised to find himself caring about her, turning what should be a cut-and-dry swindle into the most treacherous tightrope walk of his life.