Opal is not Yelena. This is good, because it gives a different viewpoint - someone who has lived their life with their family in Sitia, and bad, because Opal is not the strongest heroine. She has lots of issues (understandable from her ordeals in the Study series), but she still comes off a bit whiny in parts. Capture/re-capture is used here a lot too. It picked up by the end, but I really loved Poison Study, and I want more about Yelena and Valek, to be honest.