Taxicab driver Tom Banning is led to an abandoned bomb-site by an eight-year-old girl as an April-fool prank. The girl is later found murdered and Manning is picked up by Scotland Yard for questioning and is later arrested and charged with murder. The trial is scheduled for London's Old Bailey. Manning's wife, Jill, convinced he is innocent, fights for and wins the sympathy of Council-for-the-Defense Peter Tanner, and he is opposed at the trial by his father, prosecuting-attorney Geoffrey Tanner. The trail is presided over by Justice Harrington, whose wife is in the hospital undergoing an operation. It soon becomes evident, following the testimony of prosecution-witness Horace Clifford, that the evidence points to Manning's guilt. During a recess, Peter Tanner sees Clifford outside the courthouse, giving candy to a young girl. Farr identifies the candy as being the same brand as that found on the murdered girl. The judge's wife has died, but the trial resumes with Tanner recalling Clifford for cross-examination.