The streamer's three-part miniseries handles the aftermath of a murder case that gripped the UK in refreshingly unshowy style. “I went for a walk with my mother when I was a child, and she never made it home.” That’s the matter-of-fact, yet truly devastating, opening line which instantly proves “ The Witness ” isn’t interested in further sensationalizing one of the most sensationalized murders in recent UK history . The case of Rachel Nickell, a 23-year-old mother stabbed to death in broad