The CSIs investigate the murder of rising tennis star Claudia Weber, who was killed on a tennis court and then stuffed into the ball holder of a ball machine. Based on the bodily injuries and DNA evidence present at the scene, the CSIs determine that she was killed with her own tennis racquet on the court, but figuring out who was still around to kill her proves to be more of a challenge. At various points in the case, the evidence shifts from suspect to suspect, including Claudia's husband, her estranged brother, and a mysterious assailant from her past. Eventually, an eyewitness coupled with fingerprint evidence on a discarded tennis ball lead the CSIs to Claudia's killer: her tennis partner, Tara Janssen. Tara had been sleeping with Claudia's husband, and when she overheard him tell Claudia that he wanted to stay together and fix their marriage, she grew jealous and killed her. Meanwhile, the CSIs are surprised to learn (via an Immigrations investigator) that David Hodges has gotten engaged to an Italian bombshell named Elisabetta.