The last episode of NCIS found Lieutenant Laura Ellison in the midst of having a brush with death and talking to her late colleague, Petty Officer David Collins. He talks to her about needing to stay alive in order to keep looking into something she said she would focus on. She looks in a window to see doctors and nurses fighting to keep her body alive.
After the credits, the team is seen at a diner preparing to train for a marathon. Tim and Ellie are ready to go, but Nick is very tired and Alex just wants to eat. However, Nick mentions how good of a runner he is and this makes Tim want to catch up. He and Ellie leave to go train while they wait for their coworkers.
Meanwhile, Gibbs is at home when he gets a visit from an old friend, retired General Ellison. He has come to ask Gibbs for help at the request of his daughter, Laura, who is dying of ovarian cancer. Gibbs goes to visit her, where she informs him that she feels her friend, Collins, did not die an accidental death as previously determined. He had fallen overboard off the ship they were assigned to but she felt something more happened.
However, when Laura got sick, she couldn’t continue the fight and was hoping Gibbs could help. Back at NCIS, Torres boasts to Tim and Ellie about beating them at the end of their race. Gibbs interrupts to ask for an update, where they learn that at the time of Collins’ death, the ship’s Master at Arms, Chief Michael Vinton, had opened an investigation but it appeared to be an accidental death.
Tim and Nick go to talk to Vinton, who informs them the last person who saw Collins alive was a friend of his, Petty Officer Nicole Trainer, who has since left the Navy.
Gibbs brings Ducky to visit Laura, something she finds humorous since she hasn’t died yet. He tells her he has a friend who is doing an experimental treatment program that could extend the life of those with advanced stages of cancer. At first, Laura is unsure about doing this but decides to at least look into the possibility.
Meanwhile, Alex and Ellie interview Nicole, who thought that Collins’ death had been an accident. When they mention the fact Collins had a black eye before his death, she reveals it was due to her boyfriend at the time, Petty Officer Holden Baxter.
Nick goes with Tim to talk to Baxter, who is cocky and claims that Collins and Laura were in a relationship. He also denies being near Collins at the time of his death.
After getting the stanchion and lifeline that were on the ship when Collins fell, Abby tests it for evidence and informs Gibbs of her findings. She tells him that there was some blood on the lifeline and someone had used bleach in order to clean up evidence. They are both aware that bleach would not be used on that part of the ship and someone was hiding something.
Nick and Ellie go to talk to Laura, but Ellie does most of the talking since he is reluctant to look at Laura. She informs them she was only a friend to Collins and had been helping him to train for officer school.
After getting a smoothie from Abby, Tim tells Gibbs that they discovered at the time of Collins’ death, the ship had been seizing drugs from one area but then those same drugs were found in another country. They believe it is likely Collins discovered something was going on and this was the reason behind his death.
Up in the bullpen, Nick is acting weird as they inform Gibbs that Nicole has unexplained large amounts of cash deposits in her account. When Alex and Tim go to talk to her, they discover her body. Later, Gibbs tells Nick he wants him on protection detail for Laura in case Nicole’s killer comes after her. However, Nick is not willing to do this but relents under Gibbs’ orders.
Ducky informs Gibbs that while Nicole had drugs in her body, she was restrained and she had DNA under her fingernails. Abby informs them it belongs to Holden Baxter. Alex and Tim go to pick up Baxter, who tries to run from them. As Alex gets into the car, Tim runs after him and tackles him to the ground.
In the hospital, Laura tries to make conversation with Nick, but he is unwilling to speak. She deduces that since he is refusing to look at her, he must have lost someone to cancer. However, he is not in the mood to share.
In interrogation, Holden tells them he did go to see Nicole but only because he knew she had been connected to the drugs that were seized. He had no part in her death and had gone to see her but nothing happened. He had confronted her about the drugs but did not kill her.
Nick is standing with Laura’s father and learns that she was denied for the experimental treatment program Ducky had been looking into for her.
Gibbs goes to see Vance and talks to him about needing a favor. In the meantime, Nick has a heart to heart with Laura and opens up about losing a childhood friend to cancer. He had also been in love with her when she died.
The team tells Gibbs that at the time of the drug seizures when Nicole was involved, Chief Vinton had signed off on all the ones she was connected to. They learn he had been pushed aside for promotions and that he was under forced retirement soon.
Gibbs and Alex to go the ship, where they confront Vinton with the fact that he killed Collins to keep him quiet and he still had evidence connected to the drugs in his attack. He tries to reach for his gun, but they remind him that even if he tries to get past them, he has to get past the furious crew behind him.
Tim and Ellie confront Alex after learning she didn’t attempt to run the race with them and she had gotten an Uber for part of the trip. Their joy is short lived when they learn Torres had, indeed, run the entire way and still beat them.
After telling Laura that Vinton killed Collins, Gibbs also tells her SECNAV had gotten the information she was trying to pass along about Collins and he has posthumously been recognized as ensign. Nick comes to stay with Laura and she gives him her service warfare pin. She wants him to look at it and remember her that way. He is touched and keeps her company.