Adapted from the Graham Greene story The Basement Room, director Carol Reed's The Fallen Idol is told almost completely from a child's eye view-but it isn't a children's story. Young Bobby Henrey idolizes household butler Ralph Richardson. Therefore, when it seems as though Richardson might be implicated in a murder, Bobby does his best to throw the police off the track. The boy succeeds only in casting even more suspicion upon Richardson. As the story progresses, Henrey's hero worship is eroded by Richardson's shifty behavior, and even more so when the boy discovers that the butler's boasts of previous heroism are just so much hot air. The ending of the film differs radically from Greene's story. While it would seem that director Reed was merely paying homage to the "happy ending" philosophy (hardly likely, given the doleful climaxes of such films as Odd Man Out and The Third Man), the director had very solid reasons for altering the story: he was more fascinated by the concept of the boy's imagination nearly sending his idol to the gallows, rather than having the butler entrapped by facts. And though the ending is happy for the boy, the butler's fate is much more nebulous.
~ Hal Erickson, All Movie Guide