An early Alfred Hitchcock curiosity adapted from a stage detective story. For two thirds of its short running time it's like an old dark house horror, full of expressionist shadows and close ups of threatening hands. The last third is a chase, utilising models of various modes of transport, none of them convincing.
The MacGuffin of the search for some stolen jewels is banal, and Hitch offers little to distract us from that weakness. He doesn't tell the confusing story that well. The cast is unremarkable and John Stuart a candidate for the Master's weakest lead. Though there is the signature dark humour and eccentricity.
What is different from earlier films, is there plenty of physical action in the last third, much of it well realised. There are characters holding on to the outside a speeding train. Over the years we would see many Hitchcock heroes and villains clinging on over a precipice or some other hazard.
Hitch didn't want to make this and his relationship with British International Pictures was falling apart. It was his last production for them. The complicated story is a bit of a muddle, but if you manage to follow it, then there's just about enough of the Master here to make this passable entertainment.