The narrative proves to be an enjoyable diversion, with most of the suspense arising from the premise itself! A vessel arrives at Tilbury, and during unloading, a crate is handled without much care. A confrontation erupts between the workers, and suddenly, Leonardo Da Vinci’s celebrated “Madonna and Child” has disappeared. It's swiftly located again, but questions arise – is it genuine? Luckily, an American specialist named "Mitchell" (played by Dennis O'Keefe) happens to be present, and he soon begins pursuing a shadowy and influential swindler. Coleen Gray contributes a pleasant supporting role, and the film benefits from a capable ensemble including John Laurie and Hugh Williams; however, the production values are noticeably low-budget, with shaky camera work mirroring the flimsy nature of many of the sets. There are some intriguing shots inside London’s Tate Gallery, showcasing a more impressive assortment than the rolled-up copies of Leonardo's works that dominate the plot. Dora Bryan is reliably present behind the bar, keeping things in order, and you might recognize Leslie Phillips and Billie Whitelaw, both of whom achieved greater success later on. The film runs longer than necessary, relies somewhat heavily on dialogue, and O’Keefe’s performance feels a bit stiff, but it remains reasonably entertaining.

Source on TMDB