Summary on GoodReads.
It started really good but, as always, something went wrong in between. Well, given that Robinson publishes about six books a year... no wonder this one sounded generic.
So Mark and friends got stuck on this island that used to be home to experimental programs by Japanese. The experimental programs turned out to be Dr. Monreau-like so what is still loosed on the island are "animal-humans" made because.
Mark and friends discovered this horrible truth that was hidden in plain XXI century. They miraculously get rescued... but Mark and love interest take Lilly with them. Lilly is an animal-human who saved them and turned out to be just animal on the outside but very human on the inside.
So they take Lilly with them but keep her hidden because, what would happen if people knew that such hybrid combination was possible? She'd be taken as an experiment! - again.
At the end, Lilly laid eggs... which suggests that she wasn't only changed on the outside but inside too.
Very morbid and interesting end. Actually, Lilly laying eggs would be a much more interesting story... if Robinson and team had time to write it.
By the way, my praise to the team for writing such a damn good summary of the book. Unfortunately, the summary was better than the actual story.