The CSI's are called out to investigate the disappearance of a boy whose father died four years ago. Soon a couple is arrested at a convenience store with a boy matching the description of the missing kid. The only problem is they both claim it is their son. Both parents have exactly the same picture of the boy, with a scar on exactly the same place on his face. They hope a DNA-test could confirm who the real parents are, but when this information comes to light, it lead to another bizarre twist, possibly murder.

Sara questions her future as a CSI when a past case comes back to haunt her, the 12 year old Hannah, who has to back up her brother one more time with all new tricks up her sleeves.

A deer is illegally killed, and the person found with the body in the back of his truck apparently dressed it in a tutu. The man, who was completely drunk when arrested, was being interrogated by Nick and Brass, and suddently tries to escape and is pepper sprayed. Unfazed by the spray, officers then taser him and he bursts into flames and dies. Meanwhile an unbalanced woman wearing a tinfoil outfit at the front desk tries to warn people (including Nick) of an alien invasion. After observing the burning man, she later turns up dead with green-tinted blood. When other people turn up with the same problem, it's up to the team to figure out why. Meanwhile, an old couple dies, apparently in their sleep... but there is evidence the cases are related.

Langston is shocked when his former student is found murdered and becomes the focus of a CSI investigation into the world of Mexican wrestling.

The CSI team investigates a well-orchestrated bombing at the funeral of Officer Franklin Clark

The CSI team lends a hand to local law enforcement on the strip with several arrests until a John Doe is found in car. Also, things become personal for Captain Brass when he discovers some facts about his daughter.

When five people are killed in a small plane crash a mile off the Vegas strip, the CSI team is called to investigate. Also, Sara feels the strain of having a long-distance relationship with Grissom when a former lover of hers is involved with the crash investigation