The CSIs investigate a unique case where Russell Turner, a high school teacher, seems to have been sliced in half by a motorcyclist with a murder weapon like never before; a samurai sword. As the investigation continues, the team needs to delve into the world of Japenese mafias to find their killer. Meanwhile, Natalia suffers from the ear injury she got in the earlier explosion (810 "Count Me Out"), but when it results in a boy almost managing to kill her while she's searching Turner's home, her injury puts her and Ryan's lives in jeopardy.