Thunderbolt is the Dalmatian pups' favorite TV show hero. In the show, he is shown to be chasing Dirty Dawson, with the horse thief shooting at him. The thief then travels on foot as Thunderbolt searches. In some scenes, it shows Thunderbolt making a leap across a canyon before it seems like Dawson has shot Thunderbolt. However, Thunderbolt is only pretending, and as Dawson laughs about this, Thunderbolt then attacks and the two fall into a river, having the show end in a cliffhanger as the two are about to fall down a waterfall.
In the show, the dynamic and brave Thunderbolt is joined by his offbeat sidekick Lil' Lightning fight to defeat the evil Dirty Dawson.
In an episode, Dirty Dawson kidnaps a helpless boy named Tommy. It's up to Thunderbolt and Lil' Lightning to defeat him before any harm befalls Tommy. As Dawson ties Tommy to a moving train, Thunderbolt perches on a cliff. He jumps to the train, confronting Dawson.
Whilst Thunderbolt battles Dawson, Lil' Lightning unties Tommy. Dawson causes Thunderbolt to stumble between the train carts, and as he's about to strike Thunderbolt, another train heads by the train carts they are on, allowing Thunderbolt to get around Dawson. Thunderbolt then tangles Dawson in his own whip, tripping him up and causing him to fall into a boxcar with a mad bull. Tommy is then rescued and Thunderbolt saves the day.
While watching The Thunderbolt Adventure Hour, Patch, longing to feel one-of-a-kind like his hero Thunderbolt, hears about a chance to appear on the show while it is filming in London. However, when Roger, Anita and the 101 Dalmatians plan to move to the Dalmatian Plantation, the family move will interfere with Patch's opportunity -- until he's accidentally left behind in the commotion. Patch heads for the audition to meet his hero. Meanwhile, Thunderbolt's "trusty" sidekick, Lil' Lightning tells Thunderbolt the producers want to replace him with a younger dog.
In order to save his job, Thunderbolt decides he will go into the real world and perform an act of true heroism to prove himself. A veritable reference book to Thunderbolt's many adventures, Patch provides the perfect guide for the TV star in his attempts at real-life heroics.
At first, Thunderbolt is seen as arrogant and selfish, seeming only to care about his job and his popularity. He is very popular with other dogs, and Patch is his biggest fan, knowing all of his episodes by heart. As the film goes on, Thunderbolt becomes more kind and helpful, and he and Patch start to become friends. Furthermore, he is willing to assist those in need and is not afraid to admit that he's just an actor. Thunderbolt is also cunning and highly skilled with his acting, as seen when he tricks Cruella De Vil, the Baduns, and Lil' Lightning into believing that he is having a heart attack.
A post-credits scene shows Thunderbolt with his new sidekick Patch in his TV show, The Thunderbolt Adventure Hour.
Thunderbolt appears in "Watch for Falling Idols", where he and his creators arrive on the Dearly Farm to film their next episode. Lucky is thrilled to meet his idol and tells Thunderbolt that he's his biggest fan and has seen all of his TV shows. Before the episode is filmed, Thunderbolt is seen relaxing in a hot tub inside his trailer, where he is idolized by Lucky. However, when Lucky later finds out that Thunderbolt doesn't do his own stunts (after Thunderbolt panics from being lifted off the ground, due to his fear of heights), he shuns Thunderbolt and loses faith in him. Later on, Lucky tries to prove he's brave by climbing up the TV windmill, but ends up putting himself in danger instead. Fortunately, Thunderbolt notices Lucky in trouble and, pushing his fears aside, manages to rescue his young fan. Lucky thanks Thunderbolt who tells him that a hero isn't one who fears nothing, but is one who is willing to overcome his fears. Lucky agrees with Thunderbolt and they reconcile.
The One Hundred and One Dalmatians Diamond Edition Blu-ray features a Thunderbolt short based on early drafts of the scene, which follows the events directly from where they are seen in the animated 101 Dalmatians.
The short shows that Thunderbolt and Dawson are able to catch branches sticking from the side of the waterfall. Dawson is able to reach a ledge and as Thunderbolt's branch is about to snap, his human, the sheriff, is able to use his lasso to save him. The two pursue Dawson, but the thief uses explosives to cause an avalanche, blocking their path and allowing him to take some sacks of money from a wagon, which may be why Thunderbolt is chasing him. The sheriff thinks Dawson has escaped, but Thunderbolt climbs across the rock pile to continue the chase.