Though filmed in Hollywood, The Vicious Years is set in postwar Italy. Tommy Cook plays a homeless orphan named Mario, who happens to witness a murder committed by the son of a wealthy family. The enterprising Mario moves in with the family, promising to keep his mouth shut in exchange for food, shelter, and creature comforts. Gradually, a genuine affection develops between the boy and the family. But the homicidal son (Gar Moore) unrepentantly schemes to rid himself of Mario at the first opportunity. The slow, leisurely pace of The Vicious Years accelerates dramatically during the climactic scenes. Way down on the cast list is future MGM leading man Russ Tamblyn, here billed as Rusty.
~ Hal Erickson, All Movie Guide