Penguin’s Dutton imprint has announced plans to publish a new novel by YA author John Green on October 10, Turtles All the Way Down. This will be his first novel since The Fault in Our Stars (Dutton, 2012), which has sold 23 million copies worldwide. The book follows 16-year-old Aza Holmes as she investigates the disappearance of a fugitive billionaire, while coping with mental illness. Dutton has planned a first print run of 1.5 million copies.

Green said in a statement, “I’ve been working on Turtles All the Way Down for years, and I’m so excited to share it with readers this October. This is my first attempt to write directly about the kind of mental illness that has affected my life since childhood, so while the story is fictional, it is also quite personal.”

Julie Strauss-Gabel, president and publisher of Dutton, added, “As with all of John’s work, Turtles All the Way Down is both a singularly personal read and a catalyst for conversation and community. It is with tremendous pride and great excitement that his longtime Penguin family can finally shout this news to the world.”

Green is the recipient of the Printz Medal, a Printz Honor, and the Edgar Award, and was selected by Time in 2014 as one of the 100 Most Influential People in the World. Along with his brother, Hank, he forms one half of the Vlogbrothers, drawing millions of subscribers on YouTube. He is also the co-creator of the online educational series CrashCourse.

Green’s books have sold more than 45 million copies worldwide, and have been translated into 54 languages. The Fault in Our Stars was named Time’s #1 Fiction Book of 2012; the movie adaptation was released in June 2014 by Fox 2000 and Temple Hill.