Harry sneaks off from Slughorn’s Christmas party to follow Snape and Draco, and overhears them having an argument about Draco’s mission.
Harry becomes suspicious, but he doesn’t learn what Draco is tasked with.
Harry eavesdrops on Snape and Malfoy
Date circa December 20th, 1996
Location in Canon HBP15: The Unbreakable Vow
Type of Event Wizarding world