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One to Go
Season 9
Number 10
Writer Carol Mendelsohn
Director Naren Shankar
Original Airdate January 15, 2009
Previous Episode: 19 Down...
Next Episode: The Grave Shift

One to Go is the tenth episode in season nine of CSI: Crime Scene Investigation.


The CSI team works to close Grissom's last open case, the "Dick & Jane" murders, as Grissom prepares to leave the team for good. Before leaving, Grissom offers Dr. Raymond Langston, who helped the CSI's with the "Dick & Jane" case, a permanent position as part of the CSI team.


Picking up where "19 Down" left off, Brass identifies the new victim found under the bridge as Jeffrey Masters. His wife Maureen is missing, and Brass estimates that the team only has at most 48 hours to find her alive. After the Sheriff is briefed by Brass and Ecklie, Ecklie, who is slated to step into the Undersheriff position, tells Grissom that the sheriff has personally requested he stay on until the conclusion of the case. Continuing to work with Dr. Ray Langston, the professor whose class Nathan Haskell was speaking to from jail, the CSIs focus on what drugs Haskell might have used to subdue his male victims. Positing that Haskell had an accomplice in Langston's class, the CSIs also turn their attention to Langston's students. Brass speaks with Dan Forrester, the student who suggested getting a serial killer to talk to the class and corresponded with Haskell, but when he realizes he is a suspect, Dan tells the detective the idea came from multiple students in the class. The team visits Langston's classroom and plays the video of Haskell speaking to the class, trying to pinpoint if he made eye contact with any of the students during key comments. They zero in on a student named Thomas Donover, who asked Haskell how he controlled his victims and was told where to dump Jeffrey Masters. The police find him missing when they go to his house, and his wife Kelly insists that she does not know where he is. The CSIs search the Donover house and Greg finds shoes that match the treads found at the scene of Ian Wallace and Justine Stefani's murders. Tom is definitely the accomplice. While Tom torments Maureen, the CSIs race to isolate the location of the house where Haskell took his victims—and where Tom likely has Maureen now. Hodges discovers a kind of moss stuck in the tread of Tom's shoe that at least narrows their search to the north side of Lake Mead, but that still leaves the CSIs with a lot of ground to cover and not much time in which to do it.

Nick finds a box of video tapes in Tom's house—but no VCR around and recalls that Gerald Tolliver had a VCR but no tapes. Kelly confirms Tolliver was a friend of her husband. Catherine finds a type of sage (Salvia Divinorum) at Tom's house amongst his drugs stash that Henry confirms could have been used to subdue Haskell's male victims as it's a powerful hallucinogen. A print leads them to the dealer, but he's killed (run over accidentally) when he runs from the police. Nick views the videotapes and see Haskell's first victims, Joel and his fiancée Tiffany, with Tom Donover and Gerald Tolliver—and later spying on and filming Haskell. Grissom consults lunar charts hoping to find a way to identify the location of the house, while Langston pays Haskell a visit in jail, hoping to get the information out of him by showing him stills from the video tape spying on him. He tries to trick Haskell into thinking they already have Tom and Maureen and just want the location of the bodies of his female victims, in the hopes he betrays the location of the cottage, but Haskell sees right through his ruse and gives him nothing. Grissom uses the state/direction of the moon in the videos to find the house's location and discovers it is in Black Mesa. Brass and his team rush there and Tom is killed by a shot to the head just as he is about to murder Maureen. Brass frees her and the CSI team canvasses the house and Grissom discovers the bodies of Haskell's female victims stashed side-by-side under the floorboards of the house. The case closed, Grissom visits Langston at WLVU and suggests he apply for the new vacancy at CSI, to which he answers he'll think about it. Grissom finishes packing up his office, and despite an impassioned plea to stay from Hodges, exits CSI, catching only Catherine's eye as he walks past the team hard at work. Grissom heads to Costa Rica where he reunites with Sara Sidle as she's photographing some monkeys, kissing her passionately. She looks surprised but elated to see him as they embrace...


Main Cast

Guest Cast


David Hodges: (Walks in as Grissom is cleaning out his office): Okay. So this is really real. Fine. So, as your friend and colleague I feel that it's my obligation to inform you what a colossal mistake you're making.
Gil Grissom: Hodges...
David Hodges: Guys like us just don't get to hang it up. This job is who we are. We are the thin blue line between order and chaos. You take yourself out of the equation, who knows what's gonna happen. That's the Butterfly Effect. You taught me that. The bad guys will win more if we don't have you. Who is Watson without Sherlock Holmes?
Gil Grissom: Watson was a genius in his own right... It's the right time for me to go.
David Hodges: Okay.


  • When Grissom throws down his backpack, Sara is holding her camera on the carrying strap. But just a second later in the same scene, she has a grip on the camera's lens when they're embracing and kissing.
  • The coordinates on Grissom's GPS device don't point to Costa Rica as displayed, but rather somewhere near Arauca in Colombia, some 1000 miles offset.
  • The tracking shot of the camera on the jungle's trail disturbs the vegetation, causing movement of leaves and small branches.


  • This episode marks William Petersen's final contact appearance as a series regular as Gil Grissom.
  • William Petersen's mid-season departure is only the second in the history of the series. The first was the departure of Jorja Fox 1 year before.

See Also

CSI:Las Vegas Season 9
For WarrickThe Happy PlaceArt Imitates LifeLet It BleedLeave Out All The RestSay UncleWoulda, Coulda, ShouldaYoung Man with a Horn19 Down...One to GoThe Grave ShiftDisarmed and DangerousDeep Fried and Minty FreshMiscarriage of JusticeKill Me If You CanTurn, Turn, TurnNo Way OutMascaraThe Descent of ManA Space OddityIf I Had a Hammer...The Gone Dead TrainHog HeavenAll In

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