Sonic The Hedgehog jumps off to a fast pace with a chase scene through the streets of San Francisco. Dr. Robotic is flying after Sonic in his spaceship taking shots at Sonics as they zoom down the city streets then everything freezes with Sonic narrating about starting rewinding the story back to the beginning.
The story rewinds and we find Sonic on his home planet. Young Sonic gives the audience a quick tour of his home that looks like a direct copy of the SEGA video game with loops and jumps. He zips to his home where we meet a large owl, Long Claw who is his protector and she reminds him that he needs to be careful and keep his unique power a secret.
As Long Claw is reminding Sonic to be safe some bad guys show up to capture him. Long Claw scoops up Sonic and tries to fly him to safety but gets shot down by an arrow. With her last chance to give Sonic some direction, Long Claw gives sonic a small pouch of gold rings that can transport him to any place he thinks of. Long Claw tosses a ring that opens a portal to the planet Earth and Sonic goes through. Realizing her sacrifice, Sonic tries to run back through the portal but it disappears and Sonic is now on Earth.
10 years later….
On Earth, a Green Hills town cop who Sonic calls Donut Lord is operating a speed trap the only problem is there are no cars in sight. All of a sudden the speed radar sensor beeps at over 293 miles per hour, then again at 300mph as you see Sonic in the background with a fist pump for his high score. A puzzled Tom (Donut Lord) walks down the road and finds a blue quill in the grass that he picks up and takes with him.
Officer Tom heads back into town and Sonic saves a turtle from getting run over. Sonic then picks up the turtle and takes him for the ride of his life at super Sonic speeds down the road and lets him walk free in a forest. As Sonic sets him down the turtle jitters in shock from the fast ride.
Sonic arrives home to his cave underground and gives us a glimpse into his day to day life as he reads Flash comics, plays ping pong, and runs in a dryer which is his home gym. He goes on to explain more of the instructions he got from Long Claw. She told him if he is ever discovered to keep running and she outlined a mushroom planet to go to next if he is found on planet Earth but Sonic hates mushrooms.
As office Tom gets home for the evening he opens a letter from the San Francisco police department that informs him that he is accepted into their program. He and his wife celebrate with cake and we find out that she has already begun looking for apartments (shameless Zillow advertisement).
To get out of the cave, Sonic stops by to watch a local junior high baseball game. He hides behind the bleachers living vicariously through the lives of the young boy who hits a home run and celebrates with his teammates. After the game, Sonic runs the bases and reenacts his own game and slowly realizing he has no friends and he is all alone he grows frustrated and angry. Be begins running the bases in a loop faster and faster as his anger builds. Sonic accidentally creates a large surge of electricity that explodes in blue lightning and shuts down the entire town’s electricity.
The large electrical outage draws attention from the government who determines the well educated, 5 doctorates, perfect service record, Dr. Robotnik should be called in to take charge and find the source of the problem.
Dr. Robotnik rolls into the military camp in his large black bus and takes command of the operation. He sends his flying droid robots into the woods to look for clues. Soon, a droid finds a footprint and after a quick in-depth analysis, Dr. Robotnik determines this footprint belongs to a new species that Earth has never seen before.
Dr. Robotnik sends in the ground forces in cooperation with his robots and they close in on Sonic’s cave. Sonic begins packing up his goods and wrestles with the disappointing plan of going to the mushroom planet. Sonic decides not to transport to another plant and his shot in the leg with a tranquilizer dart by officer Tom. In the same scene, Sonic drops his gold rings pouch on the Transamerica rooftop in San Francisco.
Sonic wakes up in a pet cage inside Tom’s house and lets himself out and he talks with Tom who is surprised to find out he is friendly and can speak English. Sonic asks him for help and Tom agrees to hide him in the attic as Robotnik closes in.
Robotnik arrives at Tom’s house and the two talk about what Robotnik is looking for as Tom dodges Robotnik’s attempts to inspect the house. Instead, Robotnik sends in his mini droids to search the house without Tom’s permission. A loud crash is heard by both of them and they dart inside to see what the noise was. It appears the noise was just a raccoon that they spot eating cake on the countertop. Then as Robotnik turns away he spots the blue quill that Tom found on the roadside and a fight breaks out.
Tom punches Robotnik who falls to the ground and Sonic jumps on the droids to try bringing them to the ground. Eventually, Tom and Sonic bring the bots to the ground and make an escape in Toms truck.
On the road, Tom questions Sonic more and soon pulls over to kick Sonic out on his own so his new job in San Fransisco isn’t jeopardized. Sonic speeds west to the Pacific and returns soaking wet with a fish on his head and pleads with Tom to help him find San Francisco so he can get his rings back. Tom agrees to team up and the two hit the road to San Francisco.
On the road to San Francisco, they stop to fuel up and grab some snacks. Sonic becomes mesmerized with the Piston Pit bar-restaurant and puts on a hat and heads inside to join the fun. Tom finds him sitting at a table and is convinced to hang out for an hour and help Sonic enjoy his final days on Earth.
Tom and Sonic begin talking about a bucket list and what he wishes he could do on Earth. Sonic’s list quickly fills the page and they start to knock items off the list while at the restaurant. Eventually, a bar fight breaks out and Sonic bolts into a slow-motion scene where he moves so fast that it appears everyone else is frozen in time. Time catches up and Sonic and Tom easily win the bar fight and flee the scene.
Tom and Sonic get a hotel room for the night and he quickly runs around the room having fun and gets worn out. Sonic tells Tom he doesn’t want to go to the mushroom planet because he hates mushrooms and he likes his small town of Green Hills on Earth. Tom jokes with Sonic and tells him if he goes to the mushroom planet then he will still be a fungi (fun guy). As Sonic falls asleep he notices Sonic’s bucket list and everything is crossed off except one item that says, make a real friend.
Robotnik and his crew catch up with the aftermath of the bar fight and question some of the customers that witnessed what happened and soon they are calculating Sonic and Tom’s location.
Robotnik catches up with Sonic and Tom on the highway and launches an attack with a six-wheel tank. Sonic fights back Robotnik’s bots and discovers his electric power as he spins and knocks into the tank, stopping it in its tracks. More bots attack and Sonic fights off one after another. At the end of the battle, a small bomb explodes and knocks Sonic unconscious.
Now realizing what he is up against, Robotnik uses his laboratory to analyze the blue quill he took from Tom’s house. The blue quill blows out his lab’s power and after rebooting the lab Dr. Robotnik’s equipment shows the quill has unlimited power.
Tom takes Sonic to where his wife is staying in San Francisco, at her sister’s house. Tom’s wife and niece realize how special Sonic is and after some frantic questioning they decide to help out. Tom’s niece notices his shoes are worn and runs off to find him a new pair of running shoes (shameless plug for Puma). Tom and his wife Maddie wake up Sonic with smelling salts and he tries out his new shoes.
The three make their way downtown San Francisco to the Transamerica Pyramid building. Tom uses his badge to get a key card to the rooftop where Sonic finds his pouch of gold rings. Tom and Sonic begin to say their goodbyes and Sonic contemplates his decision to go to flee to another planet.
Sonic throws a ring to begin the process of opening a portal to another world and an incoming Robotnik bot hits the ring and they surround Tom, Maddie, and Sonic on the rooftop. Robotnik fires all his rockets and Sonic takes him by surprise.
With nowhere to run, in a surprising move, Sonic pushes Tom and Maddie off the rooftop. Sonic goes into hyper-speed which makes everything move in slow motion and similar to the previous bar fight scene he is able to point the rockets at each other.
As Tom and Maddie fall in slow motion, Robotnik catches up with his newfound unlimited energy from the blue quill he has incorporated in his ship design. At the last second Sonic is able to toss a ring to the ground so that Tom and Maddie land safely back home in Green Hills.
Sonic and Robotnik continue the chase with Robotnik right on his tale. Sonic continues to through rings and teleports all over the world from France to the Great Wall, to the Pyramids, and finally back to Green Hills.
Robotnik and Sonic continue the fight in the small town of Green Hills. Robotnik gets a good hit on Sonic and he falls to the street and is unresponsive.
The town is angry and Tom steps up to say, “He was my friend.” As soon as Tom says those words Sonic’s body begins to show bolts of blue lightning and he is revived. Sonic gathers his new powerful energy source to get his blue quill back from Robotnik.
As a final blow to knock out Robotnik, Sonic rolls into a ball and energy and begins pinging off of Robotnik’s ship (similar to the video game) and breaking up his ship until it is inoperable. Tom grabs a ring and tosses it near the ship as Sonic bangs into Robotnik’s ship to send him through the portal to the mushroom planet.
Robotnik is now gone and back at home the next day the government pays a visit to say thank you to Tom and Maddie. They claim to not know where Sonic is but after the government leaves the audience sees Sonic is in the house. Tom and Maddie tell Sonic to go to his cave and as he begins to leave they tell him to go upstairs.
In the attic Sonic finds all his personal home items from the cave are now in the attic and Tom and Maddies say, “Welcome home.”
As the credits roll we see Robotnik on the mushroom planet vowing to find a way back saying, “A lesser man would die here.” As the scene ends we see that Robotnik still has a blue quill in his possession.
Later in the credits, we see Miles, the two tail fox known as Tails, coming to Earth through a portal on a mission to find Sonic.