It's great, there's only one place I noted a slight error in the flow. "I felt a betrayer" I'd add a 'like'. But other than that, I can't spot another error on the first read-through. I would find it interesting to get a handle on Graham's own past in this issue, if only to get a taste for his underlying motivations, to lure the reader into wanting to know more about his character. I enjoyed it.