When a body is uncovered during a beach volleyball game, the evidence leads Horatio and our CSIs back into the world of H's nemesis, Walter Resden, who is now targeting an old victim and the one person Horatio has sworn to protect.

Alexx learns she may be held accountable for murder after she puts up a flier in her neighborhood warning others that a convicted child molester has moved into their neighborhood. As the CSIs unveil the evidence and their findings, it appears one of the actual neighborhood residents may not have been as welcoming of the new addition.