The CSIs investigate the murder of a dominatrix found near her secret sex dungeon.

When a young, non-verbal boy is found hiding in a stranger’s garage, the CSI team searches for his missing mother. Also, Max receives a strange letter with symbols in silver ink that Folsom and Allie recognize from prior crime scenes.

The CSIs investigate the mysterious death of a competitive eating contestant, and Chavez partners with Allie to prove where the mysterious silver ink notes have been coming from.

A silver ink note threatening Maxine Roby's life is found at the crime lab, sending the entire CSI team to crack who is behind the notes and how they connect to other murder case.