The fact that it draws from actual occurrences doesn't prevent the narrative from feeling sluggish for much of its duration. Dame Judi Dench heads up an adequate ensemble, with Sophie Cookson portraying her younger counterpart, and Tom Hughes and Stephen Campbell Moore appearing in a story concerning a domestic woman concealing a complicated history. Director Sir Trevor Nunn is unable to establish any momentum, resulting in what essentially becomes a showcase for the lead actress, who has limited screen time. It’s diverting enough, mainly because it offers glimpses into how individuals who believed they were acting appropriately during the nineteen sixties could easily be targeted by KGB agents; however, beyond that, the film feels somewhat lacking.

Source on TMDB