A family vacation turns deadly on this week's "CSI: Miami," airing tonight at 10 p.m. on CBS, and the CSIs need to find the killer before the family of the dead boy take matters into their own hands.

"I would have to say the theme of this year -- season six -- is fathers and sons," series star DAVID CARUSO tells ET. "As the viewers know from this season's premiere, it has been revealed that I have a son who is in jeopardy. We are fortunate to have DEAN CAIN as a guest star, and he [plays a man whose] son has been killed and whose second son is in jeopardy."

Cain's character is volatile, according to David, and the family is "spooky." Of course, everyone on "CSI: Miami" is a suspect, until proven otherwise, and Dean is no exception, especially when Horatio (Caruso) learns that he has purchased a gun.

"My oldest boy is killed, and I want to know what is going on," Dean explains his role. "As a parent, you want to believe that the justice system is going to do its job and find the guy, but there is also eye-for-an-eye anger: 'You touched my child, you will pay.' I don't know how you don't feel that, and my character feels that, and it manifests in his actions."

In real life, both David and Dean are fathers, which they feel helps them relate to the story.

"If I didn't have a child, I wouldn't feel as sure about the choices I make as this character. You touch my child, you have a bull's eye on your head," Dean says.

But all was not serious on the "CSI: Miami" set. While the majority of the scenes that Dean has for this episode are opposite David, he did manage to get some catch-up time with EMILY PROCTER. It turns out that the "CSI" star played Dean's fiancée, Lana Lang, in one episode of "Lois & Clark," all those years ago.