Based on the eponymous 2017 novel by Nicholas Searle , The Good Liar stars McKellen as veteran conman Roy Courtney, who thinks he's hit the jackpot when he meets rich widow Betty McLeish (Mirren) online. But what should be an easy, low-risk scam takes a sharp turn when Courtnay finds that he might be falling for his mark — and she may be hiding a trick or two of her own up those chic, silky sleeves. And if that thrumming soundtrack is any indication, it's going to be a wild ride as we find out who is the better liar in this game of sharp wits. There is no one better at double-talk and withering glances than these two.