As the veteran interrogator says right at the start, it’s all about psychology! A group of intrepid Soviet soldiers are being briefed on a very cunning plan to construct, section by section, a bridge that will lie under the waterline - hopefully undetected - thereby allowing a counter-offensive by their forces over a wide, fast flowing, river. With the Nazis all around them, their guide “Lisa” (Marguerite Chapman) and “Kulkov” (Paul Muni) find themselves in the centre of a bombing raid that sees them and seven of their enemies trapped in a cellar. Though they are outnumbered, they have the guns, the lamps and the candles and so are able to keep their enemies at bay - but for how long before the oil runs out or before the need for sleep takes over? The don’t let the grass grow, though, and as they look through the assembled junk for things to use, they discover indications that there might be an officer amongst their hostages. Officers mean information and information can be put to good use by their own, should they ever make it to daylight. What is ensues now is a cleverly crafted thriller that uses the dark, echoey and dingy surroundings of their captivity to create a tension that’s really quite effective. We, watching, have no idea whether there is anyone amongst the prisoners to confess, and with constant sounds of digging surrounding them, we also have no idea as to whether they will be found at all - and if so, by whom. Muni does most of the work here as “Kulkov” lays a few traps for his superior-minded guests and he does it quite well, with the under-used Chapman adding a little additional value too - but I thought it was actually Ludwig Donath who came across best as the slimy “Professor” whilst many of the characterisations from amidst their opposite numbers contributed an extra degree of an almost sophisticated - and defiantly psychological, brutality. There is jeopardy here, and that carries through until the very end. I wasn’t sure about George Macready as a Soviet general, but otherwise this is claustrophobically compelling watch.