The 2015 two-hour series finale of the crime procedural, which is entitled "Immortality," brought the various agents back together again for one final case. After suicide bombers detonated explosives at Catherine Willows' (Marg Helgenberger) Eclipse Casino in Las Vegas and at an auditorium at a local elementary school, Lady Heather (Melinda Clarke) emerged as a suspect.
Catherine returned from her FBI work in Los Angeles to look into the matter, while former LVPD homicide detective Jim Brass (Paul Guilfoyle) happened to be the Head of Security at the casino.
Gil Grissom, who had been working on an ocean conservation effort, joined after he had been arrested for trespassing in San Diego.
D.B. Russell (Ted Danson) asked Sara Sidle to work on the bombing investigation as well, much to her initial chagrin. They all worked alongside Greg Sanders (Eric Szmanda) and Morgan Brody (Elisabeth Harnois), to identify potential leads and suspects.
The group was ultimately successful in identifying the suspect, Mr. Betten (Doug Hutchison), who had actually been Lady Heather's first client. He was upset at Grissom for encouraging Lady Heather to stop her dominatrix business.
Morgan, Greg, and Catherine detonated three bombs that Mr. Betten was attempting to set off, and Grissom ultimately talked him out of harming himself.
In the final moments of the finale, D.B. Russell decided to move on from his post in Vegas to go to Quantico (for the spin-off CSI: Cyber), and he packed a plaque commemorating Julie Findlay (Elizabeth Shue). Ex-spouses Grissom and Sidle, once again, confessed their love for one another.
Sidle was also offered the Director position at the lab, but she appeared to decline it in order to literally sail off with Grissom in his boat, The Ishmael. Catherine Willows seemingly took on the role instead.
Sidle and Grissom will be on CSI: Vegas as a married pair, but it remains to be seen if they have been able to truly make their relationship work.
CSI: Vegas airs on Wednesdays at 10 p.m. ET on CBS. Viewers can catch up on the show on Paramount Plus.
