When Ernie tries to jump over 23 cars, he crashes and ends up going to the hospital, after which he has second thoughts about being a motorcycle stunt rider. But when some Boy Scouts are trapped on an island (after the waters knocked off the bridge), he face his fears and jumps over the river to rescue the scout troop.
A runaway named Pete idolizes Ernie Devlin and wants to be a motorcycle stunt rider like him. However, the Devlins teach this kid there's more to being a star rider.
After Sandy's misbehaving lion "Prince" escapes his cage at the circus and runs loose in town, the local sheriff is called in. While Sandy reminisces about raising the lion from a cub, Ernie and Todd work with the Sheriff to tranquilize the lion for capture before it must be put down for the sake of public safety.
After coming up with a super roller coaster stunt for Ernie, Tod feels unimportant and left out after Hank tells a reporter that about the mechanical side of the team. A representative from a rival circus offers Tod an important job as a chief mechanic. But when a tornado strikes the city, Hank is trapped in his jeep after a tree falls on it, so Tod uses his brains to rescue Hank.
A police safety inspector threatens to close Hank's circus over violations caused by the Gomez family's hot air balloon and Ernie's double loop ramp.
A motorcycle racer named Speed Simmons challenges the stunt rider to a motorcycle race.
Aunt Martha and Uncle Fred visit the Devlins when they head to their town. Aunt Martha feels that Sandy should live at their home, instead of traveling with the circus.
Sandy likes the idea that Hank hires a rock band for his circus. The band's name is Lucifer, and its lead singer goes by that stage name as well. Ernie and Tod don't like the idea of Sandy idolizing that band. But Lucifer shows his true colors by acting obnoxious and rude towards the people of the circus.
The mayor of Turtle River doesn't want Hank's circus to open, because the last traveling carnival / circus ripped off their money. When some boys (who formed the Ernie Devlin fan club) sneak in to visit Ernie, he gives a free performance for his fans. When the mayor finds out, he has Ernie arrested and thrown in jail. A forest fire breaks out near the city; Ernie helps a townsman reach the lumber mill, so he can blast the trees blocking the water supply.
Hank wants Uncle Jack, the oldest member of the circus crew, to retire. After a fire happens at the big top, one of the crew finds Jack's pipe and Hank thinks that it was his carelessness. So Uncle Jack and his dog run away. When they get the new canvas for the circus, Ernie discovers that cinders coming from a nearby lumber mill, which made small burns on the new canvas, were the cause of the fire, not Uncle Jack.
The circus caravan is stuck in a blizzard. Ernie's fear of snow reminds him of when his dad, a motorcycle cop, died during his duty. With less food and shelter for the animals, Ernie decides to overcome his fear and get help. Tod turns his motorcycle into a snowmobile.
When Jester the clown learns that the circus is heading to Southfield, he asks Hank to make a few changes; that he'd be the ringmaster (with Hank as his assistant), and that he'd go by his real name (Harry). Why? Because he has a daughter in college, and doesn't want her to know that he's really a clown.
After shows in Phoenix, Hank's circus travels to Desert City, Arizona. Along the way, the border patrol stops to inspect if there are any illegal immigrants boarding the circus caravan. When arriving in Desert City, the Devlins discover a stowaway (and runaway) named Juan. Juan wants to be part of the circus by helping Floyd out with the animals, since he's good with animals. But Hank tells him that since he's a minor and his tourist visa expired, he can't work. Juan explains that he ran away from Mexico because his dad wanted him to be a lawyer, like he is, but Juan likes working with animals a lot better.
Sandy meets Tina, a little league ballplayer, who's a fan of the Devlins' act. After seeing the billboard Hank came up with, Tina thought Sandy was a star of the circus; that got Sandy thinking of buying her own mini bike. But Ernie insists that Sandy learns the mechanics of the bike as well as driving around in circles, to handle turns.
After doing a show, the Devlins discover an intruder in their mobile home; it turns out to be a stray dog. Sandy decides to adopt the dog and name her Muffin. But before moving to the next city, Ernie decides to place an ad in the local paper regarding the lost dog. Thirty days have passed and the real owner finally shows up to claim his dog, Bridget (her real name).
The Devlins meet their dad's old police partner. He impresses the circus of his adventures since leaving the police force. Ernie and Todd don't buy his stories, though Sandy thinks they're true at first. When a pair of black panthers arrive at the circus, Floyd asks for his help, since he claimed to have experience with panthers. But then he admits the truth — all his stories were tall tales. However, Hank gives him a job as assistant ringmaster.