Alastair Sim is perfect in the role of the ostensibly bumbling "Insp. Cockrill" who arrives at a rural hospital to investigate the suspicious deaths of two of the patients. When he arrives, he encounters a staff including Trevor Howard, Leo Genn, Sally Gray, Judy Campbell & Megs Jenkins who all appear to be quite capable of being responsible - if, indeed, anyone is actually responsible - for the crimes. With V2 rockets landing all around, the race is on to prevent further killings amongst this mistrusting group of clinicians - and Christianna Brand's hero must sort it out, and pronto! The cast work really well together - even Trevor Howard who does take a while to settle in. Leo Genn is always good value, as is Jenkins and they all help to keep us guessing for much of this cracking little murder mystery. As in the best Agatha Christie tradition, the ending is a bit left field, and almost irrelevant, but that doesn't really matter; it's the performances and detection process that make this film stand out - and stand out it does.