The story begins in the dimly lit Harbaugh family basement in Ann Arbor, Mich., in 1974.
Jack Harbaugh, an assistant coach at Michigan, has taken home a canister of 16-millimeter film of an opponent. He loads the reel on a projector that shows a game on a white sheet hanging from a wall.
Jim Harbaugh, 10, along with 12-year-old brother John, take a break from playing outside, come in, sit down and watch the flickering images with their father.
They are transfixed.
The evolution of a football coach has begun.
As a kid, Jim talked about doing two things with his life. Playing football for as long as he could and then becoming a coach like his dad.
He and his brother often accompanied their father to the football offices at Michigan, where then-coach Bo Schembechler welcomed his assistants' kids. He soaked up a lot of football in those days.
One day, Schembechler returned to his desk to find Jim sitting there with his feet on it, and the chair tilted back. Soon enough, Jim would learn what it really felt like to sit in a head coach's chair.
But first, there was the issue of a playing career. After Harbaugh starred at Michigan under Schembechler, the Bears chose him in the first round of the 1987 draft. There were seven years in Chicago, and then it was on to the Colts, Ravens, Chargers, Lions and Panthers.
From there, it was a coaching career, with stops as an assistant at Western Kentucky and with the Raiders before he became a head coach at the University of San Diego and then moved on to Stanford.
By now, the 48-year-old has been exposed to many coaching methods.
"At every stop and with everyone he came in contact with, he picked up something because he knew his eventual desire was to coach," Jack Harbaugh said.
Harbaugh, who became 49ers coach in 2011, had to take a break Thursday to undergo a minor procedure for an irregular heartbeat at Stanford Hospital. He is expected back Friday to continue preparations for their Monday night game against the Bears.
Aside from his father, who remains Harbaugh's greatest influence, and big brother John, the coach of the Ravens, a handful of others helped shape the reigning NFL coach of the year.
In his office is a photo of Schembechler.
"I see him stand before a team and I hear him speak, and I swear I hear Bo's voice," Jack said. "Bo spoke in a particular cadence that Jim uses. I see so much of Bo in him."
There is some Ditka in him as well.
"The thing I took with me is the passion he had for the game, the way he was able to break the game down to what was important," Harbaugh said in a 2011 interview. "The main thing with him was the raw competition — football always came down to competing man against man, in its rawest form. He had a great way of bringing that out. Be a man. Man up. Do your job."
In 1992 Harbaugh nearly lost the portion of his body that sits above his neck after infuriating Ditka by calling an audible against the Vikings after being instructed not to do so. But today, Ditka said Harbaugh is one of the most focused and driven individuals he ever has met.
And Ditka sees a little of himself in the 49ers coach.
"The only thing I can say is we both have a great desire to win, to achieve, to be successful, to get the best out of our people," Ditka said. "That's what I tried to do, that's what he is doing."
The NFL coach who brought out the best in Harbaugh was Ted Marchibroda. The two of them helped get the Colts within one play of a Super Bowl appearance during the 1995 season.
Harbaugh began that season on the bench, and when he got his chance to play, Marchibroda told him to "let it rip." The words changed Harbaugh's mindset, and the Colts' fortunes.
"I see some of that in how he has handled Alex Smith," Jack Harbaugh said of the former No. 1 pick in the draft who has played his best football for Jim. "It's, 'I believe in you. Just go out and let it rip.'"
Al Davis, the iconic late owner of the Raiders, would allow Harbaugh to let it rip as an NFL coach for the first time. He hired Harbaugh as an offensive assistant in 2002 and exposed him to all facets of coaching and football administration.
Davis taught Harbaugh how much work it took to be a coach.
"Al challenged him, and Jim did all the grunt work," Jack Harbaugh said of his son, who often slept on a cot in the Raiders facility.
No man was more instrumental in molding Harbaugh's coaching philosophy than the late 49ers coach Bill Walsh. They never worked together, but Walsh, a former Stanford coach and consultant, endorsed Harbaugh for the Cardinal job. Over the last nine months of Walsh's life, the two would meet once or twice a month for a long lunch.
Walsh would draw out plays and tell Harbaugh about the history of the West Coast offense. How a play came about. How it evolved.
Harbaugh, pen in hand and tape recorder rolling, soaked all of it up.
"Part of his genius is he was very open about what he knew about football," Harbaugh said. "Knowledge is a powerful thing in professional sports, it's intellectual property. People try to keep others from knowing that. He was very open about sharing what he knew with assistants and people he cared about."
When Harbaugh became coach of the 49ers, he found the team and NFL Films had video libraries of Walsh coaching and installing his schemes. Harbaugh spent hours upon hours studying them.
"It's a tremendous resource," he said. "He was a master teacher."
Harbaugh has been blessed to learn from some of the best. But there also is something inside him that has made him who he is as a coach.
"I don't think I ever played with anyone at any level who is more competitive than Jim," said Tom Waddle, Harbaugh's go-to receiver with the Bears.
When Harbaugh faces his first NFL team for the first time Monday night, the Bears are likely to get a reminder of that.