Producers of CSI are promising a bloody good end to season 11. But Raymond Langston’s (Laurence Fishburne) hunt for the serial killer who stole his kidney last year isn’t the only mystery surrounding CBS’ flagship crime show. The network has yet to ink new pacts with Fishburne, Marg Helgenberger, and other costars whose contracts expire after the May 12 finale. ”It’s definitely a cliff-hanger,” teases exec producer Carol Mendelsohn. ”Most of our actors are negotiating for next season, so at the moment we don’t know. It must be a test for the writers of CSI. We always start planning for next season without knowing for sure.” Veteran costar Paul Guilfoyle is expected to stick around, but Helgenberger told PEOPLE earlier this year she’s planning to do only ”a few episodes” next season. Fishburne tells EW that he’s not looking to go anywhere. ”I’m having a great time,” he says, while acknowledging that it was a challenge replacing William Petersen’s Grissom. ”I was cognizant of the fact that Grissom was a much-beloved character. I made it my business to sit down and watch almost every episode of CSI from season 1 until I came on. It was about understanding the world and becoming as immersed in the show as possible. I love it.”

The final three episodes involve serial killer Nate Haskell (the terrific Bill Irwin) and hark back to Warrick Brown, Gary Dourdan’s character, who was killed off in season 8 — ironically, when the actor’s contract expired. The CSI crew follows Haskell to Hollywood, where they meet up with a cop (Elisabeth Harnois) who’ll join their team. ”The death of Warrick was a watershed event for all of them,” says Mendelsohn. ”Our team didn’t necessarily back him up all the way when he was shot. We wanted to do a story that would call up those memories. In the end, it is a story about whether you cross the line for a teammate.”