The sixth season of the Miami-based crime drama continues. This week, the death of a young woman in a car fire leads the CSIs to a jealous boyfriend, an unethical credit company and an attempted suicide. Elsewhere, Delko gets a helping hand from a mysterious face from his past.

Their latest case brings Horatio and the team to a beach where 19-year-old university student Jessica Taylor has perished in a car fire. The owner of the car, Brandon Fox, managed to escape the blaze but was badly injured and now lies unconscious. Analysis of an accelerant found at the scene suggests that somebody cut the car’s brake line deliberately, prior to the incident. “It’s the perfect way to start a car fire,” says Delko.

A fingerprint recovered from the brake line leads to one Andrew Hillman, who says he was Jessica’s boyfriend. The suspect claims that his prints were on the car because he helped fix it as a favour to Brandon – a friend of Jessica’s. Unconvinced by this story, Horatio accuses Hillman of attempting to kill Brandon because he was having an affair with Jessica. “The only thing you have to prove that is my prints on a burnt piece of metal,” says Hillman. “That’s all I need,” retorts Horatio.

During postmortem, however, Alexx discovers that the victim actually died from carbon-monoxide poisoning before the fire started, leading her to suspect that she and Brandon had been involved in a botched suicide attempt. Evidence supporting this theory arises when Delko revisits the crime scene and unearths a scorched piece of plastic hose used to direct exhaust fumes into the car. Though Hillman may have cut the brake line in a deliberate attempt to cause injury to Brandon, it seems he was not responsible for Jessica’s death.

A possible motive for suicide comes to light when it emerges that both Jessica and Brandon were heavily in debt to a credit company called Liberty Coast. But, when Brandon regains consciousness in hospital, he denies attempting suicide and claims to know nothing of the pipe found at the scene. “Who would want to kill Jess?” he asks. “That’s what we’re going to find out,” replies Calleigh.

Now looking for a murderer once again, the CSIs search the hose for Hillman’s prints, but instead find those of Gary Hardwick – a debt collector at Liberty Coast. Horatio and Tripp visit Hardwick at work, but he denies any involvement in the case. It then emerges that his prints were on the pipe because it was part of a beer kit he gave to Brandon when he signed up for a credit account.

The CSIs find themselves with yet another suspect when a condom found in Jessica’s flat shows that she had been having sex with a manager at Liberty Coast called Keith Reynolds. Calleigh speculates that Reynolds may have lured Jessica into debt, then offered to accept sexual favours as payment. Her suspicions are confirmed when she and Delko question Reynolds at the university campus and he immediately requests a lawyer. “Looks like we just found ourselves a prime suspect,” says Calleigh. However, just as the case looks to be nearing resolution, shots are fired and Reynolds hits the ground, dead. “The prime suspect just became a victim,” says Delko.

DNA discovered at the campus places Hardwick in the frame for Reynolds’s murder, until ballistic evidence shows that the shots actually came from a nearby harbour. If Hardwick did not kill Reynolds, then who did? And could this second killer also have been responsible for Jessica’s death?

Also this week, Delko is assisted in the case by a mysterious stranger he thinks is his dead colleague, Tim Speedle. Horatio is convinced Delko is hallucinating, until bank records show that Speedle’s account has been active for some weeks. Could Speedle really be back, or is there another force at work?