Exclusive: Cree Cicchino and Felix Mallard have landed supporting lead roles in New Line’s film adaptation of John Green’s No. 1 New York Times bestseller Turtles All the Way Down for HBO Max, Deadline has learned.

The duo joined already cast Isabela Merced in the Hannah Marks directed feature.

Turtles All the Way Down tackles anxiety through its 17-year-old protagonist, Aza Holmes. It’s not easy being Aza, but she’s trying… trying to be a good daughter, a good friend, and a good student, all while navigating an endless barrage of invasive, obsessive thoughts that she cannot control. When she reconnects with Davis, her childhood crush, Aza is confronted with fundamental questions about her potential for love, happiness, friendship, and hope in the face of her mental illness.

Cicchino will play the role of Daisy, while Mallard will portray Davis.

The novel debuted as an instant No. 1 bestseller,...