Which CSI episode is listed as the series' 100th milestone?

“Ch-Ch-Changes” is listed as CSI: Crime Scene Investigation's 100th episode milestone. It is the eighth episode of season five and aired on November 18, 2004, marking a major achievement for a series that had premiered only four years earlier.

The episode follows Grissom and his team as they investigate the murder and mutilation of Wendy Garner, a transgender woman. The case takes the investigators into Las Vegas's transgender community and examines mistaken identity, prejudice, and the dangers created by an unlicensed medical practitioner.

The milestone is easy to confuse with other numbered episodes. “Mascara” is the series' 200th episode, while “Frame by Frame” is the 300th. “Grave Danger” is a major season-five story but is episodes 116 and 117 overall, not episode 100. “Ch-Ch-Changes” also became one of CSI's most-watched broadcasts, drawing more than 31 million U.S. viewers.