It's actually not half bad.  You have a decent premise with good potential for some fun scenes.  I'd think it would be easier for readers to get into if some of the language were cleaned up, but I'm getting the sense that this is more of a language barrier issue than just being a sloppy writer grammatically, because this is actually reasonably clean.  Your dialogue feels sort of stilted in places, but that just goes back to the same reason, I think.  All in all, not bad; perhaps try saying some of the dialogue aloud to yourself, odd as that may sound, to try to find the right tone.  Keep it up.