It's 2007, and a young Reed Richards is in school giving a presentation on his ambition to create a teleportation device. He is scolded by his teacher, who tells him that he was supposed to talk about his career ambitions and not fantasy (because the teacher is a *****e).
Ben Grimm is in the same class. We see him return home to his family's car part... place where he is smacked around by his big brother (also a *****e). Ben investigates a noise outside, and finds Reeds rummaging for parts. The two go back to Reed's home where he has built that teleportation device in his garage. They turn it on, and it works, making a toy car disappear, though it kills the power to houses all over the neighbourhood.
Jump 7 years later, and the pair are at a science fair showing off a revised version of the device. They successfully transport a toy plane away, and this time reverse the process to bring it back. The same teacher as before again scolds the boys for attempting to sell a 'magic trick' as science. Never-the-less, they catch the attention of Franklin Storm (accompanied by his adopted daughter Sue), who tells them that they are not moving the object to some undisclosed location, they are in fact transporting it back and forth between dimensions. He offers them a place at his lab, as this is the very thing his team have been working on.
Reed enrolls at the Baxter building, and Ben bids him fair well, saying that Reed is finally home. Franklin tracks down Victor, a former student who was kicked out for poor behavior. He already developed the technology to transport objects to another dimension, but could never crack the method to bring things back. He is offered another chance to be involved in the project.
Johnny Storm is injured in a street drag race, and told by his father Franklin that he has to work for him to pay back the damages to the car Franklin paid for. He is a skilled mechanic, and 'can build anything'.
They all work together and build a fully functioning dimension jumping device. The board who funds the project witness a successful test involving a monkey, and decide to move on to human subjects. They don't want to use the scientists however, and intend to pass the project over to Nasa. Victor hates those guys already, and after a few drinks, Victor, Reed and Johnny decide to make the trip first. Reed calls Ben to come with them, as he was there when Reed first dreamed up the idea.
The four of them travel to the other dimension, where Victor disrupts some volcanic green energy substance and everything goes bad. As they flee to the device, Victor falls into the substance and the rest jump into their pods. Back on earth, Sue has become aware of the unauthorised trip and helps them get back. Everything goes bang upon their arrival, and the Fantastic Four are born.
They are taken to a secure facility where their powers can be contained in seperate units. Reed hears Ben calling for help and crawls through the air vents to get to him. Alarms sound, Reed panics and escapes the facility, leaving Ben behind.
Jump ahead a year. Ben is being used as a weapon by the military. Sue and Johnny are honing their own powers. A new device is being built, and there is an uneasy relationship with the government as they do what they are told in the hopes of finding a cure. Reed is off on his own, cobbling together gadgets of his own. He is desperate to find a cure for his friends. Believing he'll be needed to fix their situation, Sue aids in the search for Reed. He is located and Ben brings him in. The two hash out their differences on the plane ride back.
A team of red shirts jump into the other dimension, and discover that Victor is still alive. They bring him back, but things go badly imediately as the distrusting and frankly crazy Victor rejects the government and goes on a murder spree. He decides humanity have already ruined their world, and he won't let them ruin 'his'. He returns to the other dimension, and opens a wormhole thing that begins sucking in the facility on earth and the surrounding area. The Fantastic Four follow him over and fight it out. Doom is eventually disintergrated in the portal and the team escape back through it before it closes.
The team then reject any more orders from the government, and are given a space to work free from intrusion. They ponder names, and there's a cheesy Age of Ultron style cut before the name is given.
Credits.