Rio is the first episode of Season 5 of CSI: Miami.
Horatio and Delko travel to Rio to find Riaz, the man responsible for Marisol's murder. While there, Horatio meets Yelina and learns that his brother is back doing undercover work and may be connected to Riaz, for whom Horatio also suspects his nephew is working. Back in Miami, Natalia, now a CSI, helps Ryan investigate the beating death of a woman in Coral Gables.
- It's revealed that Natalia is now an official CSI.
- With Horatio out of the country, Calleigh is temporarily promoted to the rank of Lt. and as such becomes the head of the Miami-Dade Crime Lab.
- Horatio eventually learns from Yelina that Ray Jr might be working for the drug lord now.
- Raymond is eventually discovered in a slum, bleeding and eventually dies from his wounds, his last words being to Horatio whom he urges to save his son, Ray Jr.
- Horatio and Delko eventually succeed in avenging Marisol's death by killing Antonio Riaz.