Play Dead is a non-series title by Peter Dickinson. It was one of the Open Road freebies back in December, but if you missed it then, it has dropped to $1.99 at Kindle and Kobo US now, and is couponable/VIPable at Kobo.
Kindle US:
https://www.amazon.com/gp/product/B00VSLI6O2
Kobo US:
https://www.kobo.com/us/en/ebook/play-dead-21