As indicated by its title, Thou Shalt Not Kill is a strange blend of religiosity and crime melodrama. Charles Bickford plays Reverend Chris, a popular neighborhood clergyman who hopes to clear young Allen Stevens (Owen Davis Jr.) from a murder charge. Complicating matters is the fact that the real criminal has told Reverend Chris the truth during Confessional. How can the priest reveal what he knows without violating the edicts of his religion? Suffice to say he solves the problem, though not as inventively as Montgomery Clift in Hitchcock's I Confess (1953).
by Hal Erickson synopsis