The film’s conclusion offers some sort of explanation, yet I mostly felt uneasy about what was happening at the “Jefferson” house. Dan (Dean Jagger) and his wife Lucille (Helen Hayes) are parents to three sons; two are serving in the army, while their third son, John (Robert Walker), has just come back from Washington, but seems troubled. He’s lost interest in going to church, doesn't care about his friends or usual activities, and receives phone calls from people who won’t leave messages. His parents casually discuss the situation with Stedman (Van Heflin) while he’s visiting, and initially he dismisses it lightly. Then he shows up seeking reimbursement of around $18 for the repair, after which his presence and the overall feel of the movie shift toward something more ominous. It portrays a nation where communist fears are everywhere, even in quiet communities where people jump to conclusions based on rumors and create their own narratives. The central question is: who has “John” become? I felt the plot was too flimsy and wandered aimlessly, needing greater depth to carry it through its just over two-hour length. However, Helen Hayes’ performance stands out; Jagger is reliably good, but it's Hayes whose character displays increasing confusion, inner turmoil, and doubt, giving a compelling portrayal as we approach an ending that challenges her maternal feelings. The final scene carries a sense of dread or perhaps encouragement, though you’ll have to stick around to see it for yourself. Possibly, if the film had been thirty minutes shorter and more tightly directed, it might have improved. As it stands, it's often quite boring.

Source on TMDB