Harry Potter first travelled via the Floo Network in 1992 when he journeyed from The Burrow to London. However, instead of saying "Diagon Alley", Harry was nervous and said "diagonally". Therefore he accidentally ended up at Borgin and Burkes in Knockturn Alley.

In Harry Potter and the Chamber of Secrets, Harry mispronounces "Diagon Alley" as "Diagonally" while using Floo Powder for the first time. Because he is nervous and accidentally inhales a bit of hot ash, his voice cracks, and the Floo Network misinterprets his destination. Instead of arriving in the bustling shopping district, he is whisked away to a fireplace in Borgin and Burkes, a shop specializing in Dark Arts artifacts located in the much grittier Knockturn Alley. This "wrong turn" serves as a pivotal moment in the story, allowing Harry to overhear Lucius Malfoy discussing the sale of incriminating items and foreshadowing the darker themes of the series. In the 2026 "Wizarding World" theme parks, this moment is often referenced in the immersive design of the Knockturn Alley section, which is intentionally kept dim, cool, and slightly eerie to contrast with the bright, whimsical atmosphere of the main Diagon Alley area.