Gary Sinise is set for a key series regular role opposite Dylan Minnette in the fourth and final season of Netflix’s YA drama 13 Reasons Why.

Sinise, who is expected to appear in every episode, will play Dr. Robert Ellman, a compassionate, incisive, no-nonsense adolescent and family therapist who works to help Clay Jensen (Minnette) battle anxiety, depression, and grief. Formidable, intense, and deeply humane, Ellman is steadfast in guiding Clay to accept the help he needs so desperately, to come to terms with the trauma in his past, and begin the process of healing.

“From the first moments we conceived of the role, I thought of Gary Sinise, but hardly dared to dream it might happen,” said series creator Brian Yorkey. “A consummate actor and first-rate human, Gary brings the exact combination of toughness, smarts, and heart the character needs. We’re all thrilled and honored to have him join us for this pivotal role in our final season.”

The final season of the drama from Paramount Television and Anonymous Content will feature the core cast’s graduation.

Minnette, Brandon Flynn, Justin Prentice, Alisha Boe, Christian Navarro, Miles Heizer, Devin Druid, Ross Butler, Timothy Granaderos, Anne Winters, Steven Weber, Brenda Strong, Amy Hargreaves and Grace Saif star.

Yorkey serves as showrunner and executive produces of Season 3 alongside Mandy Teefey, Kristel Laiblin, Selena Gomez and Joy Gorman.

Sinise is known for his roles in films such as Forrest Gump, which earned him an Oscar nomination, and Apollo 13, and for starring on all nine seasons of CSI: NY. He also starred for two seasons on CBS’ Criminal Minds: Beyond Borders. His upcoming films include Good Joe Bell starring Mark Wahlberg and Connie Britton, and I Still Believe starring Riverdale’s KJ Apa and Britt Robertson. He is repped by CAA, Brillstein Entertainment Partners and Gochman Law Group.