It's the era of the superhero.
Mr. Incredible and Elastigirl are two of the top crime fighters in the game, and, even better, they're about to be married. Cue wedding bells.
While on his way to the wedding, Mr. Incredible is forced to deal with typical superhero stuff. You know: thieves, bank robbers, bomb-loving mimes. The usual. A young fanboy named Buddy Pine shows up in the midst of this confrontation, demanding that he become Mr. Incredible's sidekick. Mr. Incredible refuses, of course, but not before accidentally derailing a train.
He saves the passengers, but they sue him anyway—as does an attempted suicide victim who he saved during that whole ordeal. (For real.) In response, the government enacts the Superhero Relocation Program, which bans heroes from using their powers and demands that they anonymously rejoin society.
So Mr. Incredible is now Bob Parr, and Elastigirl is Helen Parr. They have three kids: Violet, who can turn invisible; Dash, who has super speed; and Jack-Jack, who…doesn't have any powers except being a baby. Bob works at an insurance agency and to put it frankly, he's pretty miserable.
Bob pines for his former life as a superhero. His way of coping? Going out on late-night, crime-fighting runs with a former superhero pal—which does not go unnoticed by Helen. She's furious that Bob is reliving his glory days at the expense of his family.
One day, Bob gets so frustrated with his job that he throws his boss through several walls with his super strength. (Bet the guy didn't see that coming.) So does he get arrested for assault? Nah. He's fired, of course, but the government lets him off the hook. He doesn't tell Helen any of this, either.
When he returns home that night, he finds a strange tablet in his bag that plays a video of a tantalizing offer from a woman named Mirage. She wants him to become Mr. Incredible again to stop a rogue robot from destroying a secret government facility. His dream come true, Bob tells Helen that he's going to an insurance conference and heads to the mysterious island, where he easily defeats the robot, dubbed the Omnidroid.
Bob is revitalized when he returns home. He works out a bunch and even gets himself a sports car. In other words…he has a midlife crisis. Helen grows suspicious with all the change in attitude and wheels—not suspicious that he's secretly moonlighting as a superhero, but that he's having an affair. Whoopsie.
She knows something is up when he heads off to another "conference." In reality, Bob is heading back to the mysterious island for another job, where Mirage promises he will now meet the benefactor behind his missions.
That benefactor is revealed to be a super villain named Syndrome…once known as Buddy Pine. Broken-hearted by Mr. Incredible's rejection way back when, Buddy turned his prodigious intellect to evil, building the Omnidroid and using it to kill a bunch of former superheroes. He plans on releasing the Omnidroid into a city after defeating Mr. Incredible, then stopping the robot himself and pretending to be a hero.
While Mr. Incredible is held prisoner by Syndrome, Helen (who's now figured out what's really going on with her hubby) leaps into action. She contacts Edna, former superhero costume designer, and learns that she recently made a new costume for Bob at his request. Conveniently, Edna decided to make costumes for the whole family. Dressed in her sleek new suit, Helen tracks Bob's location with a homing beacon embedded in his costume before hopping onto a jet to rescue her man.
Unbeknownst to her, there are two stowaways aboard: Dash and Violet. She doesn't have much of a chance to get angry, however, because the jet is shot down out of the sky by Syndrome. Bob hears this happen over the radio and assumes that his family is dead.
But they're not. (Obviously; what kind of depressing and short movie would that be?)
They managed to survive the crash and have snuck onto Syndrome's island. There, Helen heads into the belly of the beast to save Bob, while the kids are instructed to stay behind and lay low.
Long story short, Helen rescues Bob—but not before Syndrome launches the Omnidroid into civilization. With the fearsome robot wreaking havoc in New York City, and Syndrome handily bested by his own creation and unable to stop it as planned, the family rushes back to save the day.
With the family now working as a team, the Omnidroid is no big deal at all. They take the robo-moster out and return home to check up on Jack-Jack, assuming that the day has been successfully saved.
But wait; there's more.
The Parrs get home only to discover that Syndrome is in the process of kidnapping Jack-Jack. They're even more shocked when Jack-Jack doesn't really need saving—the little dude transforms into a bunch of strange and fearsome forms, revealing himself to have ample superpowers and causing Syndrome to drop him. Syndrome is killed in the ensuing chaos and the day is saved once again.
For real this time.
With their adventure behind them, the Parr family is closer than ever. Bob and Helen have rediscovered their spark; Dash is now allowed to play sports despite his super speed; and Violet now has the confidence to approach her crush. So, the family seems happy and content as they exit one of Dash's track meets…
...only to be met by a new super villain: the suspiciously mole-like Underminer. Before you have the chance to say "incredible," the family already has their costumes on, showing that this superhero team-up was no one time lark. See you at the sequel, folks.