Dale has recently become hooked on a popular tv series called "Flash The Wonderdog", which features the exploits of a crime-fighting dog. But Chip thinks he is getting too obsessed with it and, one day, shuts the tv off in the middle of an exciting fight scene. He tells Dale that the whole series is faked, but Dale refuses to believe it and the two chipmunks start quarrelling.
Meanwhile, Fat Cat is also watching "Flash The Wonderdog". However, he is not a fan of the show; rather, he has plans to ruin Flash's reputation. He and his gang go to the tv studio where the series is filmed and kidnap Flash from his dressing room. Back at Rescue Ranger Headquarters, Dale learns of Flash's disappearance via a news report and hurries to tell the others.
At first, Chip thinks Dale has simply watched "Flash The Wonderdog" once too often and refuses to help. But the other Rangers talk him round (as Monty says, "how can we say we're willing to rescue anybody if we ain't willing to rescue everybody?") and they set out in the Ranger Plane to look for Flash. Meanwhile, Fat Cat and his stooges disguise themselves as Flash and start committing various acts of sabotage.
After hours of fruitless searching for Flash, Chip is about to give up. But Dale refuses to consider it and even tries Flash's battle howl, hoping the dog will hear it. Moments later, the Rangers hear Flash's answering howl coming from a derelict building and go inside to investigate. There, they see Meps lying asleep, a cheese sandwich clutched in his paw, and try to sneak past. But the cheese brings on one of Monty's cheese attacks and he wakes Meps when he swipes it.
The Rangers find Flash in a locked room, which they enter via a hole in the door. But Flash is too big to get out that way so Zipper unpicks the lock and the Rangers open the door - to find Meps waiting for them. Monty pulls Meps' hat over his eyes and orders Flash and the Rangers to run for it. The Rangers make it back to the Ranger Plane, but the floor gives way while there is still a wide gap separating them from Flash. Dale tells Flash to jump the gap, but Flash is afraid of heights and is unable to do so.
Then, as Meps corners him, Flash falls. The Rangers give chase in the Ranger Plane and, as Flash clings to a streetlamp attached to the side of the building, Gadget deploys the grappling hook, which Zipper attaches to an awning, turning it into a safety net. But Flash continues to cling to his precarious perch, too terrified to jump to safety. Moments later, just as Gadget is about to suggest something, the streetlamp breaks under his weight and he falls, sliding down the awning and landing in a pile of tyres. Most of the Rangers are relieved to have saved Flash, but Dale feels betrayed.
Flash tells Dale that he is "just a tv actor" and leaves to head back to his studio. Later, back at Ranger Headquarters, Dale sits dejectedly at the table, refusing to take an interest in anything his friends suggest and not even speaking to any of them. Even when Chip suggests watching tv, this has no effect. But Chip turns the tv on anyway, just in time to hear a news report about Flash's alleged crimewave. The Rangers quickly realise that Flash is being framed and even Dale snaps out of his unhappy mood. He says that, even though Flash isn't the hero he believed him to be, he is not a bad guy either.
Meanwhile, the producer of the "Flash The Wonderdog" tv show attends a press conference at which he says he will be hiring Flash's sidekick, Conrad Cockatoo, as the show's new star; the show will now be called "Conrad The Wonderbird". On hearing this, Fat Cat is furious and demands to know when they will give the starring role to a cat. Just then, Meps comes in and tells Fat Cat that Flash has escaped. Fat Cat immediately realises that the Rangers were involved and, after depositing Meps through a trapdoor in the floor, starts plotting to go on nationwide tv dressed as Flash and attack Conrad.
When Flash arrives back at the tv studio, he sees a crowd of people waiting for him. At first, he thinks they are fans come to welcome him back, but it soon becomes clear that they are not; instead, they want to catch him for his supposed misdeeds. Flash runs into the studio, just as the Rangers catch up with him in the Ranger Plane. Inside, he tries to beg Conrad to help him. But Conrad panics and the producer, thinking Flash wants to hurt Conrad, orders the production staff to put up a standby sign and capture Flash. There follows a wild chase through the studio and Flash is eventually forced to fight his fear of heights and climb the ladder leading to a narrow walkway.
Down below, Fat Cat (dressed in his "Flash The Wonderdog" costume) snatches Conrad off his perch. Flash and the Rangers quickly realise what is going on and Gadget hatches a plan to expose Fat Cat for the impostor he is. She tells Monty to turn one of the tv cameras around, while she and Zipper handle things in the control room. Meanwhile, Chip and Dale (who are on the walkway with Flash) beg the dog to help Conrad.
Suddenly, Flash's battle howl echoes through the studio as he swings on a rope with Dale riding on his head. Then, seconds after Zipper activates the camera Monty turned round, Flash pulls off the mask Fat Cat is wearing. But Fat Cat is not beaten yet. He grabs Conrad and, with his stooges circling him, threatens to kill the cockatoo unless Flash backs off. Luckily, Chip and Dale come to the rescue by turning a firehose on Fat Cat and his gang and sending them flying out of the studio on jets of water. Afterwards, the producer tells Flash he knew all along that he was innocent and apologises.
As the Rangers are leaving, Flash goes to thank them for helping him look like a real hero. Gadget tells him he did it by himself and Chip makes him an honorary Ranger. Grateful, Flash hugs Chip and Dale, leaving muddy pawprints on their fur.