"The Green Tree is the code," she whispered. "For the security system."
It seems you are looking for an article based on the keyword — which strongly suggests a connection to The Silent Patient by Alex Michaelides, a global bestseller often featured on "P" lists (like P opular, P sychological thrillers, or P ublishers' weekly top charts), or possibly a reference to a P odcast or P latform ranking.
While some seasoned thriller readers might spot the clues early (the focus on Theo’s timeline, his specific knowledge), the execution is satisfying. It shifts the question from “Why did she do it?” to “Who is really on trial?”