As usual, the season begins by picking up the pieces of the cliffhanger from the season before. At the end of the third season, Gibbs had quit the NCIS after a terrorist attack he warned them about went unheeded.

“Shalom” puts Ziva on the run after she’s framed for murdering a high ranking government employee. At this point Tony is in charge of the team. They have to get Gibbs back, though, and the story wraps satisfactorily in “Escaped.”

Cutting edge technology gets featured in “Singled Out,” and the subject matter involving a kidnapped Navy computer specialist allows McGee and Abby to thrive in their element while driving Gibbs crazy with their techno-babble. Mike Franks, Gibbs’s NCIS mentor, returns to the series in “Faking It” and fans get more background on what Gibbs was like when he was first starting out. “Dead and Unburied” is a nifty little mystery.

The pace picks up again with “Witch Hunt,” the series’ first Halloween episode. Some of the lines and the situations Gibbs and his team delivered and found themselves in left me laughing so hard I thought I was going to die. This episode alone is priceless. “Sandblast” brings Gibbs and Lt. Colonel Hollis Mann, Gibbs’s present girlfriend, together on a case again, and it’s always fun to watch these two work through things. In a later episode, “Sharif Returns,” they get to finish the work they start here.

“Once a Hero” centers on a decorated Marine, and fans of the show know that anything involving Marines is one of Gibbs’s red flags. He’ll stop at nothing to do what he needs to do to take care of those people. “Twisted Sister” brings McGee into conflict with himself over the NCIS and his sister. “Smoked” puts Gibbs together with FBI agent Fornell in a search for a serial killer. As fans know, there’s a lot of history between Gibbs and Fornell, and not all of it is good.

Science comes to the forefront again in “Driven,” and McGee and Abby are in artificial intelligence heaven as they try to figure out how a murder was done. The murder of a Marine puts Gibbs at odds with a county sheriff in “Suspicion.” Ducky moves into the spotlight in “Blowback” when he has to go undercover in a high-tech black market ring. “Friends and Lovers” showcases a murder that turns intriguing, but it’s Tony’s undercover work that gets the lion’s share of the attention.

“Dead Man Walking” is a tug at the heartstrings as Ziva becomes involved with a dying Navy lieutenant. This episode was almost too predictable, but still watchable. “Skeletons” is the search for yet another serial killer (there are a lot of these in police shows of late). “Iceman” is a straightforward mystery with the twist of the “dead” man coming back to life long enough to point in the direction of his murderer.