Dr. Sam Beckett is a brilliant genius physicist with six doctoral degrees. He is working on "Project Quantum Leap" in a concealed government laboratory in the southwestern desert of the United States near the end of the 20th century. He grew up in Indiana in a loving home and had a sister who was abused by her husband. In Season 1, Sam calls his father on the telephone to tell him, while only identifying himself as a relative, that he regretted never telling his father that he loved him. Sam's father responded that "He knew" saying that a father always knows how his son feels about him.

One of Sam's trademarks is that at the end of each episode, Sam "leaps" into the setting for the next episode, usually uttering a dismayed "Oh, boy!"