Erin couldn't be happier. She was in a great relationship with Halstead, had a great job, and was clean. She had everything she could ever want. Until she meets Thea, a young girl with a heart problem. As the two get to know one another, Erin realizes there is more than meets the eye with Thea. Especially since she has seen those eyes before.

When a young foster child was the only witness and survivor to a quadruple homicide, the CSI's attempted to get her to reveal the killer's identity. What if she would not talk? How would they catch their killer? Smacked!