It's hard for me to get into a thriller unless there's something unique about the premise, and from this excerpt, there so far isn't anything unique. Sibling strife, and especially twin strife, isn't that uncommon, and the excerpt didn't show me any interesting twists. I also think I know what the conclusion will be, but of course that would remain to be seen if I read the actual book. Maybe there is something surprising, but it wasn't revealed in this excerpt.