This is a prequel short story told by Thomas, set the summer before Don't Let The Forest In.
It happens one day before the flashback on page 208 in the book. It contains the slightest of spoilers for Don't Let The Forest In, but as a prequel you can technically read it without reading the book first.
It's told by Thomas Rye (which means you get to see Andrew through his eyes) and it's set the summer before the events of Don't Let The Forest In — that is, before everything went very, very badly!
I hope you enjoy letting the forest in once more and spending just a little more time with Andrew, Thomas, and Dove. I don't imagine I'll ever write more of them, so this is the bittersweet last time.