Sometimes it’s easy to talk about a film or a play without giving away too many spoilers. However, in the case of The Good Liar, it’s virtually impossible. Roy and Betty meet over dinner, having been chatting on a dating website; he seems in frail health so, a few nights later, Betty allows him to stay over in her house rather than walking all the way up the stairs to his own apartment. But, actually,he’s in perfect health and appears to be part of a gang – or at least a partnership – of swindlers, defrauding greedy but stupid investors of their hard earned cash. OK – that’s not too much of an opening spoiler.

There is, however, a basic twist to the story – and let’s face it, it wouldn’t be much of a thriller if there wasn’t, so that in itself isn’t a spoiler. However, if you have any inkling of this twist in advance, it will completely ruin it for you. So, if you want a quick spoiler-free review, all I’ll say is that it’s enjoyable, well-performed, although with some unnecessary gore and unexpectedly bad language from Sir Ian, and, frankly, in some respects rather an unpleasant film. If you like the sound of a dramatic pairing between Sir Ian McKellen and Dame Helen Mirren, then you’ll love it. And who wouldn’t fancy that? Now, if you want no more spoilers, bookmark this page, go and see the film and then come back. In the meantime, the rest of us will get on with dissecting it….

… I think they’ve gone. Phew! Now I can tell you what I really think. SPOILER ALERT!!! (Just in case) The strength and weakness of this film is in the casting. Sir Ian and Dame Helen are a powerful combo, and there are many exciting, tense, witty and dramatic scenes between the two. But do you really think an actor like Dame Helen would have taken a role as an elderly woman defrauded of her assets, made to look stupid and weak? Naaaa. Now, if it had been Dame Judi, she might have built up an emotional image of noble fragility and crumbled beautifully in front of us all as a downtrodden old dear. But this is Dame Helen. From the Janis Joplin-like Maggie in David Hare’s Teeth ‘n’ Smiles to D.I. Jane Tennison and many roles before or after, she’s always the spunky, spiky, unpredictable, gritty strong woman. And if anyone’s going to outsmart Sir Ian’s Roy, it’s her Betty. I’m sure I’m not the only person who thought right from the start of the film that her character has her own agenda.

Revenge is a dish best served cold, they say, and that’s proved without a doubt in this finely-detailed plot to put right a wrong over half a century old. No wonder it’s set in 2009; if it had been set in 2019, the past would probably be too distant for them to do anything about it. When you discover the elaborateness of the pre-planning, before the substance of the film gets underway, you feel both wow, that’s clever and wow, that’s far-fetched in about 50-50 measure. Nevertheless, the film does weave an enjoyably intricate web of deceit that is entertaining to observe, and, despite the occasional horror and gore, there is something delightfully British afternoon-tea about the whole thing. At times it feels like an episode of Midsomer Murders as directed by Quentin Tarantino.

Sir Ian and Dame Helen dominate the film throughout, and with acting of their quality, that’s no surprise. A very small cast adds to a sense of claustrophobia. Personally, I find it hard to watch Jim Carter and not see Mr Carson from Downton Abbey; here he plays Roy’s partner-in-crime Vincent, like a spiv Mr Carson, hair bouffoned up and with a constant eye for a cash deal. Russell Tovey plays Russell Tovey playing Stephen, Betty’s grandson, a suspicious lad with an unexpected grasp of Nazi history, who spends most of the film acting as Roy’s chauffeur with bad grace. There’s a nice performance from Mark Lewis Jones as Bryn, the hapless investor who bumbles his way through a deal and is sacrificed for his pains. But there’s no doubt the film belongs to its two big stars.

Mrs Chrisparkle was finding it a very unhappy film until the twist started to reveal itself; clearly she was empathising with Betty just a wee bit too much, and it’s just a bit too unimaginative to base a plot on a ruthless old git manipulating an innocent old girl. But Dame Helen isn’t an innocent old girl, never has been, never will be. Very watchable and enjoyable, a couple of moments when my dislike of violence made my stomach retch slightly, and an ending where one plot to deceive fails catastrophically and another plot succeeds miraculously. Recommended, but primarily for the acting.