Sonic 3 Movie Spoilers & Full Plot Summary

Sonic the Hedgehog 3 is here, and following the sequel’s introduction of Knuckles and Tails, the new installment introduces another iconic character from the franchise: Shadow.

The whole cast that audiences know and love returns for this installment, joined by talented new faces, including Kristen Ritter’s Director Rockwell and Keanu Reeves’ Shadow. Jim Carrey also gets to pull double duty, donning loads of prosthetics to play Doctor Robotnik’s grandfather.

Shadow Gets Loose From Prison Island

The movie opens on Prison Island, where some guards are watching over Shadow, who is sleeping safe and sound in a containment tube.

Suddenly, a heartbeat registers on the monitor—Shadow is waking up. Doctor Robotnik’s logo flashes on the screen as the guards start to panic.

Before everyone knows it, Shadow breaks free with his chaos energy, literally wiping the floor with every guard in the room. Brief flashes give glimpses of Shadow’s tragic origin story, which centers around a close relationship with a child named Maria.

Leaving the facility, Shadow heads to the nearest city, which happens to be Toyko.

Now, audiences are with Sonic the Hedgehog at his home. He’s about to race Knuckles and Tails to prove he’s the fastest.

However, the race is a fluke and a ruse all to surprise Sonic for his B-Earth-Day (the anniversary of his first day on Earth). The festivities with Team Sonic, Tom, and Maddie don’t last long before Krysten Ritter’s Director Rockwell and G.U.N. arrive to ask for their help.

Team Sonic accepts the mission and is taken to Toyko to help bring down Shadow. Needless to say, their first brawl does not go as planned.

Shadow easily defeats all three of them. Even Sonic fails in his second attempt to fight Shadow, who is now sporting a fancy motorcycle.

An Unexpected Team-Up Between Sonic and Robotnik

The plot then pivots into an advertisement for Chao Garden, a Tokyo food establishment where Team Sonic debriefs with Tom Butler’s Commander Walters.

Their debrief is interrupted by an army of Robotnik’s drones, who attack the team and Walters, blowing up their table. At the last minute, a mystery motorcycleman comes in and, pulling off some fancy moves, wipes out the drones.

After getting an important keycard from Walters, Team Sonic chases the mystery man down, who is none other than Lee Majdoub’s Agent Stone. He claims Robotnik isn’t behind this, and he’ll prove it.

Taking Team Sonic into his crab robot fortress, they surprise an overweight, sulking Robotnik. The group begrudgingly agrees to team up to track down Shadow and find out who is doing all of this.

The story jumps back to Shadow, who is browsing the ruins of his old stomping grounds. More flashes of his past go across the screen, revealing tender moments between Maria (the daughter of the Professor in charge of Shadow) and himself as they bond.

As Shadow and Maria lay under the stars, it’s reiterated that he arrived in a meteor and knows nothing about his home.

His memories are interrupted by the Professor, whose identity remains hidden from viewers, meeting back up with Shadow after fifty years.

The Professor Revealed, He Wants the Eclipse Canon

Team Sonic, with Robotnik, all arrive at the destroyed facility to find Shadow.

They split into three groups: Knuckles, Tails, and Doctor Stone, and Sonic and Robotnik. Shadow surprises all of them in record time and captures them.

Well, all of them but Robotnik, who instead gets to meet the mystery man behind it all. It turns out that the professor in charge of Shadow is Robotnik’s grandfather, Gerald.

He’s been locked away for fifty years—but now he’s ready to exact revenge against G.U.N. for what they did to Maria.

To do this, the Professor aims to take control of the Eclipse Canon, built under G.U.N. Headquarters in London. The weapon can launch a precision strike anywhere on Earth but requires two keycards to activate—one from Commander Walters and another from the HQ behind a vault.

Robotnik decides to team up with his father alongside Shadow and a hesitant Agent Stone. Before they leave, Shadow attempts to wipe out Team Sonic with a black hole, but the trio escape thanks to one of Tail’s rings.

Team Sonic Plans a G.U.N. Heist

Now, it's time for Team Sonic to ask for help, which leads them to Tom and Maddie, who need a respite from their boring lives.

After establishing that using the Master Emerald isn't an option, they devised an alternative plan to get into G.U.N Headquarters.

Tom and Maddie will utilize holographic tech (housed in an incredibly obvious Tail-themed pin on their collars) to disguise themselves to get past the entrance. Their first choices are to impersonate Natasha Rothwell’s Rachel (Maddie’s sister) and Shemar Moore’s Randall.

Once inside, they will get into the server room, take over the servers, and lower the protective barrier around the building. Then, Sonic will swoop in, past the lasers, and into the vault, grabbing the key.

However, things take a different turn when it's revealed that the Robotniks are already there.

A brief cutaway to Shadow and Doctor Stone starts to reveal that Shadow and the Professor may have darker plans than anyone suspected. Stone is clearly getting worried—though he doesn't have much time to worry as Tail flushes them out of the sewer system.

Back at the HQ, dancing to "Galvanize" by The Chemical Brothers, the duo easily get through the lasers ahead of the vault in their laser-reflective suits. Sonic joins at the last moment, but before they can grab the keycard, Director Rockwell activates the gravity traps on the floor, stopping everyone in their tracks.

It’s a trap, and G.U.N. was expecting them.

Thankfully, Knuckles breaks through the ceiling and saves everyone, causing gravity to go haywire in the process. A fun scene plays out while everyone races to the keycard, as people go up and down as gravity switches back and forth.

Sonic proves his speed by breaking through a gravity well in order to save Tom and Maddie from falling debris.

He runs outside the vault for a last-minute save to catch up with Rockwell. Under the holographic guise of Commander Walters, he tricks her into giving him the key.

His victory is short when Shadow catches up and punches Tom, thinking that he’s Walters. Sonic arrives and is furious.

Shadow leaves while everyone gathers at Tom’s body.

Golden Sonic to the Rescue

Sonic is angry. He demands to get the Master Emerald to stop Shadow’s evil plan from happening.

While hesitant initially, Knuckles caves, saying he trusts Sonic, warning that his anger and thirst for vengeance aren't good.

After retrieving the Master Emerald from Adam Pally’s Wade (a fun payoff from the Knuckles Paramount+ series), Sonic uses its powers to go Golden Sonic.

Meanwhile, the Hyperion Canon is floating about Earth. Shadow charges up the weapon with his chaos energy—but is quickly interrupted by Sonic, who blasts through the window.

The two have an absolutely brutal fight as they smash and teleport across Earth. While Shadow is taking a beating, he’s still holding his ground against Sonic.

In the spaceship, The Professor reveals their true plan to his son: to wipe out Earth and reset humanity completely. The grief he feels for Maria’s loss is intense, so much so that everything must go.

Surprisingly, Robotnik isn't too keen on the idea. After all, what is there to even rule at that point? Father and son turn against each other as the former villain works to save the world instead.

Meanwhile, the fight between Sonic and Shadow continues to rage as they both receive the Master Emerald power-up. Their brutal fight eventually reaches the moon, where Sonic gets the upper hand and wins.

However, before following through with his vengeance, Sonic realizes this anger isn't him. This gives Shadow an important moment to reflect, realizing the mistakes he’s also made.

He recalls the last time he sat under the stars, which was with Maria, and how she said, “A light shines even though the star is gone.”

The duo agrees to team up and try to stop the canon before it destroys Earth.

Sonic and Shadow Work Together to Save Earth

On the ship, the family feud isn't going well for young Robotnik. In fact, he basically loses before being saved by Tails and Knuckles (thanks to a ring).

His son’s last-minute save surprises the Professor, as Robotnik shoots his grandfather into the spinning chaos energy generator, killing him like a zapped fly.

Sonic and Shadow are forced to fight a horse of mechs being dropped from the Canon in defense as they make their way to the death beam. Just as the death beam is about to launch into Earth, the duo tanks it, blocking it from going further.

Robotnik, Knuckles, and Tails work to aim the giant laser away from Earth. They succeed but end up grazing the Moon by accident.

Sonic falls to Earth but is saved thanks to the combined efforts of Tails and Knuckles.

Shadow, however, must sacrifice himself to help push the canon away from Earth as it's about to explode into a deadly radioactive ball.

During his final moments aboard the vessel, Robotnik gives an emotional last live stream, including a farewell to Dr. Stone. As it blows up, so does Jim Carrey’s iconic villain.

The movie's final scene sees Tom recovering and okay as Sonic, Tails, and Knuckles race off for real.

Introducing Amy Rose and Metal Sonic

The post-credits scene for the film will undoubtedly have people talking.

Taking place right after the end of the movie, Sonic overshoots the finish line and ends up in New York. There, he’s met by a new threat: Metal Sonic.

But there isn't just one of them; there’s a whole army. Thankfully, a new friend arrives to help him out.

Audiences meet Amy Rose, Sonic's biggest and most obsessive fan from the original games.

The second post-credits scene reveals that, to the surprise of literally nobody, Shadow is alive and well on Earth as he picks up one of his limiter bands.

Sonic the Hedgehog 3 is now playing in theaters worldwide.

Make sure to pick up a fun Sonic-themed popcorn bucket on your way to see the movie!