The news are full of the magical weapon the enemy is using againt Rhonia, a blue fog that drains the odic life force of everything it touches. There are hints that despite the donations from all over the country, people on the front survive only on black-market imports from
who-knows-where. As students at the Thaumaturgical Academy, Andy and Leonie understand more of this than most 13-year-olds. But the war seems a long way off on this sunny October day, at the old magical refinery near Andy's hometown, where they've been evacuated to.
Andy, Leonie, Ryan and Mike came here for a camping trip. But when they arrive, they find that someone has recently been using a lot of magic there. And when they try to find out what is going on, they suddenly find themselves locked in by the refinery's repeller fence, with a group of nasty-looking soldiers who are reactivating the machines to refine odic force. Soon, it becomes clear that they have stumbled on a far-reaching plot and that the only thing keeping them alive is that the soldiers don't know they are there.
And that's scary indeed. For if they don't come back tomorrow, their families will come and look for them. And if the kids can't find a way to get a message to them, when they see there is someone at the old factory, they will ring the doorbell and ask them whether they have
seen a group of children...
I like the idea. You've got some major problems with the hook. Start with the kids at the refinery. Leave out all that stuff about the war.
Mostly though, even though I like the idea there's not a chance I'll read the pages cause you've got some really clunky writing going on here: "where they've been evacuated to"; "for if they don't" that bodes ill for the pages.
You need a critique group. You've got a good idea, you just need to work on the writing. And writing is learned. Everyone who cackles and points a claw at clunky writing has penned a lot of it too. Miss Snark herself spent many an uncomfy hour in the hot seat at the Writing Center at Chasing Boys University learning how to pare and prune. To this day she has "second sets of trusted eyes" for important documents (primarily love haiku to entice Mr. Clooney).