The episode is "The Incredible World of Horace Ford" (Season 4, Episode 15). Horace Ford (Pat Hingle a/k/a Dr. Grant Ormsbee in "The Defector," "Man on Fire," and "To Kill a Mind") comes to grips with the unpleasant memories of his childhood, memories that he has kept blocked out in adulthood. It is a painful realization, and it is one that we all encounter at some point in our lives.
We see what an outstanding actor Mr. Hingle was in this episode. He portrays a very talented, yet somewhat eccentric toy designer. He also portrays a man whose mind has reverted to childhood, causing him to react as a child would to the goings on around him.
Ford's colleague is Leonard O'Brien (Philip E. Pine a/k/a Tyler Skaggs in "Full Fathom Five," Toshi Nomuru in "Which Way Did They Go?" and Bajano in "The Gunrunner").
Jack also appeared with Pat Hingle in "Cat on a Hot Tin Roof" (Broadway, 1955) and with Philip E. Pine in "Face of a Shadow" (12 O'Clock High, 1966) and "The Jake Lingle Killing," (The Untouchables, 1959)