Hill Harper and Harold Perrineau, <i>CSI: NY</i> Hill Harper and Harold Perrineau, CSI: NY

On Wednesday's CSI: NY, Sheldon Hawkes' visit to a Pennsylvania prison provides him with a jarring revelation and puts him in a fight for his life.

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In the episode, Hawkes (Hill Harper) receives word that death-row inmate Reggie Tifford (guest star Harold Perrineau) wants to speak with Hawkes before he dies. During their meeting, Tifford shares some unsettling news with Hawkes, who unfortunately doesn't have any time to process what he's just heard.

"The prison gets put on lockdown, and there's a prison riot," Harper tells TVGuide.com. "And obviously, being a police officer in a prison riot is probably one of the most dangerous positions anyone could ever be in. It's almost like a death sentence."

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Perrineau, who's familiar with prison scenes thanks to his role on HBO's Oz, says his character actually tries to protect Hawkes during the riot, but that's a tense proposition. "He wronged Hawkes," Perrineau says. "After the riot breaks out, he then tries to protect Hawkes, but Hawkes doesn't want the protection because I did him wrong. I did something really awful to him."Harper says the revelation hits his character very close to home, and even makes him reconsider some of his choices. "It makes him take stock of and reexamine how he treated his family in the past," Harper says. "He's forced to deal with this person who is a convicted murderer, but he also has to look in the mirror and see how he did not treat people as well as they should have been treated."Perrineau says his character does get some redemption. "That's a theme for me," he says with a laugh, referencing his return to Lost, which also aired this week. "Eventually, he really does redeem himself. He helps Hawkes through this thing as he helps him solve a case."

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At the center of the riot is famed CSI: NY serial killer Shane Casey (Edward Furlong). "There's no question that the Shane Casey character is the worst villain in all six seasons we've had on our show," Harper says. "This is such a genius way of showing how diabolical he really is. He is just bad news."Harper says the episode will explain how Casey's fingerprints ended up on Danny's badge earlier this season and sets the stage for a huge finale."You never know what he's going to do," Harper says. "And that is revealed in a very dangerous way in the finale. He takes an action that I think is going to surprise everybody with how scary it is, and that's the way the season's going to end. It's pretty exciting."CSI: NY airs Wednesday at 10/9c on CBS.