Of course it is about a teen, Joe who is a "Walker".
He might be a direction blind like me, who get lost in his own house. But he could walk into another dimension. And go into In-Between world and train as a young agents, with the other versions of himself in other worlds.
The premise is interesting. It is more like a teenage summer movie, so you know what to expect. It is nice, short and fun.
Almost done. It is a fast read. And there are still emotional bits regarding responsibility and power.
Kind of like Spiderman.
I hope for a good ending. Joe is a good kid.
The team first mission failed. So, he got his memory wiped. A bit like MIB.
So, somehow plot moved along.
I would expect a bit more interpersonal relationships. Maybe too short a book for that. The characters are all right, but they could do a bit more interaction to give it a bit more background.
All in all. A good book for young persons.