Really enjoyed it, despite a few implausible incidents. Kept me guessing right to the end with fresh twists.
Just a point of information: my daughter has done a bit of lecturing at Cambridge. She's had to deal with plagiarism, usually from internet sources. They way to detect it, she says, is to find a short but distinctive phrase or sentence from the essay and paste it into Google. You don't paste in a whole paragraph, because if it's been edited in any way, there won't be a match. Then once you have matched the source, you've got 'em!