Sara Sidle makes a desperate call on her walkie as she clutches Captain Jim Brass' arm. This harrowing scene, one of the first three stills released from the "CSI" series finale, appears to take place outside of what looks like Lady Heather's home.

Could this spell trouble for the dominatrix-turned-sex therapist and possibly her and Sidle's shared love interest, Gil Grissom?

CBS has released a few first looks from the two-part episode titled "Immortality" that will find Grissom (William Petersen) and Catherine Willows (Marg Helgenberger) returning to Las Vegas to solve a catastrophic case that paralyzes all of Sin City.

Petersen and Helgenberger both return to reprise the roles they originated on the CBS procedural 15 years ago along with other series original Paul Guilfoyle, who plays Captain Brass. The photos also feature series regulars Ted Danson as D.B. Russell and Jorja Fox as Sara Sidle.

In a second photo, Brass and Willows are seen walking up to a crime scene that already has a fire engine on scene. A couple FBI agents hang in the background, which could explain Catherine's arrival given she left Las Vegas to join the federal agency during season 12.

The final photo shows Russell and Sidle look ready to assess a crime scene as EMT workers attend to several victims on the floor of a casino.

Check back with HNGN for more news and photos from the "CSI" finale.

"CSI" will air its final two-part episode on Sunday, Sept. 27 at 9 p.m. on CBS.