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.