"NCIS" returned from winter hiatus last week with an episode that ended on a nail-biting cliffhanger.

In "Kill Chain," the team investigates the death of an officer named Daniel Coyne, who was shot by an American surveillance drone.

It turns out that Coyne had previously participated in a raid in Pakistan that was meant as a response to the bombing that killed Sec Nav. The raid was considered a success at the time, but a known terrorist named Benham Parsa was able to escape with a drone that crashed during the raid.

Coyne was the operator of the drone that the enemy recovered, so the team assumes that his death was in retaliation.

Delilah (Margo Harshman) is involved in the case to provide information. This is unfortunate for McGee (Sean Murray), who is squabbling with her over his reluctance to attend her gala.

Gibbs' (Mark Harmon) ex, Hollis Mann (Susanna Thompson), also gets involved when the team learns that she is investigating the contractors who built the missing drone.

Gibbs is not happy about her reappearance, as she broke his heart years ago. They try to make peace with one another, and Mann makes a confession. She tells him, "I liked you, okay? I really liked you. What happened between us was good - great even. But there was a wall that wasn't coming down - your past."

Later, the team finds a woman named Pace, who worked for the contractor and was with Coyne was he was killed. They learn that she was willing to sell information to Parsa for cash.

They finally track down Parsa, and find out that his next target is the gala Delilah and McGee (who finally agrees to go) are attending.

The team is too late, and the drone hits the gala. Delilah is badly hurt by shrapnel, but McGee is unharmed because he was outside at the time talking to Tony (Michael Weatherly), who had called to warn him about the attack.

Gibbs and Mann go after Parsa, but he escapes. Gibbs put Bishop (Emily Wickersham) to work to find Parsa, even though Bishop wants to go to the hospital to see McGee.

"Come on, this is what you do," Gibbs tells Bishop. "Get to work. You find him."

On the next episode, "Double Back," Gibbs and the rest of the team will track down one of Parsa's henchmen in the hopes of finding the elusive terrorist. Meanwhile, McGee will struggle with the ramifications of the attack, as Delilah is in critical condition. Also, Wendy Makkena will return as Dr. Rachel Cranston.

TVLine reported that McGee's personal issues will persist into upcoming episodes. 

Watch the promo for "Double Back," which airs Tuesday, Jan 14 at 8 p.m. on CBS.