Garry Shandling was one of the sharpest and most innovative American comedic minds of the past century, and his death two years ago at the age of 66 was, to put it mildly, a huge fucking loss for the planet. His disciple Judd Apatow knows that better than most, and is determined to ensure Shandling’s legacy gets its due.

The Zen Diaries Of Garry Shandling is a new two-part, four-and-a-half-hour documentary directed by Apatow, and judging by the above trailer, it looks to be an ambitiously exhaustive deep dive into the life and mind of Shandling and the people he influenced. As Apatow himself admits during the two-minute-plus trailer, it was hard for even Shandling’s closest friends and colleagues to feel like they truly knew him. But through on-camera interviews with the comic himself—as well as discussions with friends and admirers like James L. Brooks, Jim Carrey, Conan O’Brien, Bob Saget, Jerry Seinfeld, Sarah Silverman, and more—the film tries to trace not only his enormous impact on comedy, but also the man himself and how he evolved through the decades into someone actively working to open himself up to the world and the people around him. His voluminous journals, which the comedian began as normal diaries but that slowly transformed into analytic and psychological studies of his journey through comedy and Buddhism, provide an entry point for the film. For fans of Garry Shandling—or fans of any of the comics who looked to him for inspiration, really—the documentary should be a must-watch.

The Zen Diaries Of Garry Shandling will air over two nights on HBO: Monday, March 26 and Tuesday, 27, with both airings at 8 p.m. ET.