If you’ve ever seen Girls, you’ve probably noticed Lena Dunham’s Eloise tattoo on the small of her back. She’s long been inspired by the children’s story of a young girl living in the Plaza Hotel, and a couple years ago, Dunham got to meet the books’ illustrator, Hilary Knight, after a friend of Knight’s told him about her tattoo. That meeting — and their later friendship — inspired Dunham to executive-produce a documentary on his life called It’s Me, Hilary: The Man Who Drew Eloise that premiered at Sundance and will air on HBO March 23. Here’s the charming first trailer.