A violent murder in a casino parking garage and another episode in the police interview room lead the CSIs to one shocking discovery after another. The case involves a missing woman, a long dead body and a missing child.

Grissom, Catherine and Nick investigate the death of a runner during a competition. Meanwhile Sara and Warrick investigate the death of a 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.