The season finale of "NCIS: Los Angeles" picks up where we left off. The team is reeling after the death of Michelle, Sam's wife.
Callen suggests to Sam that he go spend time with his children. But he has other ideas. He wants to find Tahir, the Sudanese terrorist responsible for his wife's death.
Sam is reluctant to have Callen join him. He initially tells Callen to get out of the car. Callen tells Sam, "We are partners through good and bad." Sam starts to cry. "I'm going to hurt people, G." Sam and Callen drive away from the scene.
The coroner's van carrying Michelle's body is rear-ended by a vehicle. The driver of the van gets out and a woman is there. It seems like a typical fender bender, but it's really a trap. Tahir emerges with a gun. The woman is an accomplice. They hijack the coroner's van.
Callen and Sam were unaware of the van hijacking as they drove to a mosque. Sam says he's going inside to talk to an imam. Callen finds out about the van and realizes that Sam hasn't come out yet. Callen goes inside and the imam approaches him. He hands Callen something in a white cloth. It's Sam's NCIS badge. Sam is gone.
Callen calls Eric and asks to track Sam, but there's no response. Sam's phone is offline.
With Sam now solo, he heads to his house to get weapons. As he packs a bag of guns and ammo, a man enters the room. It's Sabatino, the CIA agent who helped Sam in the last episode. "Are you ready?" Sabatino asks Sam. "I am now," Sam says.
Callen headed to Sam's house and just misses him. He sees the gun cabinet opened and the missing weapons. He calls Sam and leaves a message urging him to let them help him.
Meanwhile, Deeks and Kensi are following Tahir's trail, which leads them to an office building. They walk into one of the rooms and there are photos of Michelle on the wall. When Callen arrives, a sniper fires a shot through the window and hits Callen. Luckily for Callen he was wearing a vest and the bullet didn't severely injure him.
With the help of Nell, Callen leaves the scene in an ambulance. That gave the team enough cover to get out. Deeks and Kensi are safe.
Sabatino and Sam are in a car and Sabatino hands over a file on people they're tracking. One is a rich Kuwaiti who might have information on Tahir. Sabatino and Sam decide to go question him.
They walk into a club and they meet with the Kuwaiti. He plays it close to the vest and acts like he hasn't heard of Tahir. Things turn violent as Sam and Sabatino take down his guards and Sam grabs the Kuwaiti. He demands information, and gets it. The Kuwaiti shares information that leads them to Little Ethiopia.
The rest of the NCIS team is working a lead after they get a hit on the coroner's van. They find the van, but it's empty. Michelle's body isn't inside. There is a cell phone and it rings. It's Tahir. Deeks picks up the phone and Tahir asks to talk to Sam Hanna. Tahir has an ultimatum: Get Sam on the phone or he will start sending back pieces of his wife.
With Sam off the grid, the team needs a backup plan. Tahir calls back and they use Sam's voicemail greeting to communicate with Tahir. Tahir wants to meet and gives a location.
After the phone call, Eric asks, "What do we do now?" It's a good question, since Sam is away from the team. Callen's response: "We find Sam."
Sam and Sabatino are in Little Ethiopia. They're gearing up to ambush a location that may or may not have a connection to Tahir. Sabatino thanks Sam for letting him help. (Sabatino used to work with Sam's wife.) But Sam wants to go solo again. He puts Sabatino in a sleeper hold and says he's the only one that's expendable. He handcuffs Sabatino to an ATM machine and drives away.
When Sabatino wakes up from his temporary slumber, he calls Callen and tells him that Sam is about to walk into a gunfight. He gives away the location and Callen and the team head to the scene.
As Sam gets ready to go in, the cops arrive and startle him. He goes to leave and Deeks and Kensi try to stop him, but he ignores them. He gets in his SUV and attempts to drive away, but Callen is in his path.
Sam gets out of the SUV and tells Callen to move. Callen wants to help. He tells Sam about Tahir and Tahir's location. Sam wants to go himself, but Callen urges him to allow them to help. The rest of the team wants to help Sam. He finally concedes. He walks back to the SUV and says, "Are you coming or not?"
They head to a busy area in Los Angeles and Sam is waiting at a curb. Callen, Deeks and Nell are at different positions at street level. Kensi is the sniper on a rooftop. They spot a man who matches Tahir's description, but it's not him.
A tour bus pulls up and the driver — the woman who is helping Tahir — tells Sam to get on the bus. Sam gets on and heads to the back. Tahir is sitting in the back of the bus.
Tahir warns Sam that if he tries anything, he'll start shooting passengers. He has other accomplices on the bus. He tells Sam to give him his hand. He handcuffs Sam. "I don't want you running away," Tahir says.
Sam asks where his wife is. Tahir says Sam doesn't have much time left. The team decides to ambush the bus. They take out the driver and Callen boards the bus. He takes out two of Tahir's accomplices as Sam struggles with Tahir. Sam realizes that Tahir has a dead man's switch. He's wearing a suicide bomber's vest.
There's no way for Sam to disarm the vest, so they need to take drastic action. Callen shoots off the chain of the handcuffs so Sam can escape. They jump out of the back of the bus just as the vest explodes and destroys the bus.
Sam and Callen are fine. Tahir is dead.
After the experience, Kensi and Nell have a moment as they talk about the importance of life and relationships. You can see Kensi realize that she has to do something. She asks a police officer for a flash bang, she pulls the pin and tosses it in the bomb disposal container. She approaches Deeks and asks to speak with him.
And here's the surprise of the episode: She gets down on one knee! Kensi proposes to Deeks. The ring for Deeks: The pin from the flashbang.
"I want to spend the rest of what I have with you," Kensi says.
Deeks says yes. "I love you," he says.
The season concludes with Sam and Callen at the morgue. Sam says his life will never be the same without his wife. Callen says he's here for Sam. "We all are," he adds. "We always will be."
Sam kisses Michelle on the head and asks Callen to take care of Hetty and the team until he gets back. With Tahir dead, Sam is going to spend some time with his kids.