Summary (from Goodreads):
“Identical twins. Identical DNA. Identical suspects. It’s Pretty Little Liars meets Revenge in this edge-of-your-seat thriller with a shocking twist.
When they were little, Lexi and her identical twin, Ava, made up a third sister, Alicia. If something broke? Alicia did it. Cookies got eaten? Alicia’s guilty. Alicia was always to blame for everything. The game is all grown up now that the girls are seniors. They use Alicia as their cover to go out with boys who are hot but not exactly dating material. Boys they’d never, ever be with in real life.
Now one of the guys Alicia went out with has turned up dead, and Lexi wants to stop the game for good. As coincidences start piling up, Ava insists that if they follow the rules for being Alicia, everything will be fine. But when another boy is killed, the DNA evidence and surveillance photos point to only one suspect: Alicia. The girl who doesn’t exist. As she runs from the cops, Lexi has to find the truth before another boy is murdered. Because either Ava is a killer…or Alicia is real.”
The Third Twin was just really fun. I read it in one sitting, unable to put it down and trying to figure out exactly what was going on and whether it was possible that Lexi was crazy or an otherwise unreliable narrator.
I did guess part of the end reveal (there are enough twists and turns that I feel confident in saying that it’s very unlikely someone will correctly be able to guess everything) but that didn’t affect my enjoyment at all.
Highly recommended—and now I want to read her entire backlist.