Warrick, Catherine, and Nick try to determine the cause of a house fire that kills a teenage kill. The fire is in the same neighborhood as a similar arson fire. Grissom and Sara investigate a man found dead with letter tiles in his stomach. The man was a competitor in a word game tournament.

Grissom, Catherine and Nick investigate the death of a runner during a competition. Meanwhile Sara and Warrick investigate the death of couple in a hotel room, initially thought to be a murder-suicide. Both cases take place during this 'cop' competition , with more than 20.000 attendants (all of them cops). This gives the investigations an interesting turn, as almost all the suspects and all dead people are cops.

Grissom and Sara may be secret lovers, but they still find ways to surprise each other like when their religious beliefs surface when two nuns find a body of a woman crucified on a makeshift cross. The woman was found in a church where the priest may be a man of sin instead of a man of God.

Season finale: The investigation of a triple homicide leads to the discovery of corruption running rampant throughout the LVPD. The closer they get to the truth, the more serious are the repercussions. To be continued...