Emma and Henri are as close as sisters can be. They have plans to be mad old cat women when they're ancient. In fact, they have their whole lives planned out. Then Emma betrays Henri and the two girls relationship goes sour.
And then they get stranded on a desert island together.
I've given it four stars because I think it was quite well written and it kept me guessing and I liked the toxicity of the sisters' relationship.
I think the romantic element with Alex probably wasn't necessary, but he was another facet that kept me guessing and the girls played him off against each other, so he added to the general poisonous atmosphere.
The dual timelines were good and I liked seeing the lead up to the two sisters falling out. In fact, both time lines kept me guessing to the end.
The ending was wrapped up nice and neatly, so no room for a sequel.
Eh. Four stars. I liked it four stars' worth. Maybe three.