On the Hogwarts Express.
Harry Potter and Ron Weasley first meet Hermione Granger in “Harry Potter and the Philosopher’s Stone” (released as “Harry Potter and the Sorcerer’s Stone” in the U.S.) on the Hogwarts Express, the train that takes students to Hogwarts School of Witchcraft and Wizardry. Hermione enters their compartment looking for Neville Longbottom’s lost toad. Hermione comes off as a bit of a know-it-all in their first meeting, lecturing Ron about the proper way to perform a spell and questioning Harry about his scar. Despite this somewhat awkward first meeting, the trio eventually become best friends.