The CSIs arrive to investigate the death of a man shot in front of his house. A woman runs towards the scene crying that the decease was her husband. Moments later, another woman also claims that she is the dead man's wife. It turns out that the three people were a committed threesome. The other case starts with the discovery of a woman dressed as a mermaid found inside the river.

After a routine call leads two of the team into an explosion the CSI's face a race against time to find the bomber and the possibility of losing one of their own.