Dexter 'Dex' Drabner is an agent with the SSSK.
That is the Super-Secret Spy Kid organization. This is the part where I normally talk a bit about the spy agency but since I am told nothing other than its name, well, I can tell you nothing, other than its name. I mean it! Even the acronym SSSK is something I came up with. Not the name, though; it's for real.
When we first encounter Dex, aka The Spy Next Door, he is held in the clutches of the evil Commandant Cranium, about to be cut to pieces by the evil man's Death Dicer, "a swinging globe covered in blades that would chop him up into bite-size ... bits". That is when, using just a paperclip, Dex frees himself, grabs his nearby skateboard, snatches the thumb drive he was there to retrieve, and makes his escape. All very dramatic and sensational and ... well, that's about when Dex wakes up safely in his own bed. He had been up late working on a school essay on what his dream job would be and he had been answering being like his hero, Toby Falcon, world-famous professional skateboarder and hero of the Skate Spy movies.
His dreams are the only exciting part to Dex's very humdrum world, except for the occasional and totally unpleasant run-ins with Millicent, his next-door neighbor and "the biggest bully on the block". His home is boring. School is boring. His life is boring. Those Falcon movies are really the only thing that is not boring and they are not even real!
That will all change when he goes in search of a mutant rat in his school. How the rat became mutant and how it got free and therefore needed hunting, well, that is a good chunk of the first adventure so you'll have to read it yourself. The important thing here is that it does and he does and that is how he ends up in the secret underground headquarters of an eye-patched subway musician - well, if you heard her play, you would argue that last bit.
She is Big K (Bid Kid in Charge) of the Super-Secret Spy Kids, Girder City Chapter. And she is in a tizzy because her best agent, Toby Falcon (yep, he really is a secret agent), is missing. There is just one thing that can help and that is if Dex Drabner, average third grader that he is, becomes her newest agent and saves the day. Is he qualified? Nope. Does that matter? Nope.
But he is given B.O.A.R.D. which stands for Battery Operated Artificial Reasoning Device. It is a skateboard that is so much more and is super cool and likely to get someone like me killed in minutes but Dex has a blast with it.