A young Buck falls off his bike, and his parents appear angry with him. After his dad relents, Buck realizes that getting himself hurt is the way to get his parent’s attention, and he continues to do so throughout adolescence.
In the present day, Maddie tells Buck that their brother Daniel was diagnosed with leukemia and that their parents had Buck amid his treatment, hoping he would be a match for a bone marrow transplant.
Unfortunately, he matched, but the grafts wouldn’t take, and Daniel later died. Buck brushes Maddie off and ignores her.
Flashbacks shows Buck reaching out to Maddie for help, as he struggles at home with her gone and married to Doug. She gifts him her truck and tells him to leave home, and tentatively agrees to go with him before changing her mind.
He then sends her updates of his life via postcards, and he travels and lives in a variety of places.
The 118 fights a five-alarm factory fire, and after Buck goes off to help the team on the other side of the building, he gets lost after finding the last factory worker, Saleh. They get trapped by fire, and after an explosion, Saleh is trapped under a vat.
Once the sprinklers come on, Buck attempts to lift the vat, and with the aid of the 118, they are able to rescue Saleh.
The Buckley’s visit Buck and tell him they are proud of him for saving lives, and after Chimney tells him that Maddie never left with him in the past because of Doug’s violence, he makes amends with his sister.