You know, this isn't normally how query letters are written, but I totally dig it! It's unique, sets up the story, and catches my attention. I'd definitely pick this up just because the story itself is so intriguing and unusual, and your letter definitely reflects that vibe. Great job!
I only have a couple of sugesstions. At the end of your query you stated Anders knows he has to be careful or he could kill Randy, then the next sentence is about how Randy discovers what Anders is doing but it might not be in time to keep Anders from killing him. I interpret this as Anders doesn't want to kill Randy, but in the very next sentence he does. I would tweak this a little to say something about Anders motivation, like "Anders learns he is causing Randy's illness, and if he's not careful, he could end up killing him, which would end his own life since the two are connected." Not that awkward and clunky, but you get the idea. The only other thing is to round up your word count to 85,000 words since you don't have to have an exact count listed in your letter.
Nice work with this. Do you have the first five pages posted? I'd love to get a glimpse.