A routine late-night technology upgrade at the NCIS headquarters turned into a murder scene when an intruder began hunting inside the darkened building. NCIS Season 23 Episode 17 titled Reboot brought back a familiar face to help solve the case, but the episode ended with a shocking discovery that changed everything.
The April 21 episode saw LL Cool J return as Sam Hanna for a special guest appearance. His character found himself at the Navy Yard during a long layover, just as chaos broke loose. What started as Kasie Hines leading a two-hour system reboot quickly became a high-stakes fight through powerless hallways.
The episode began with a plumber visiting a home to fix a bathroom sink. After completing the job, he noticed no one was responding to his calls. When he walked into the living room, he found a mother and her two children tied up. Before he could help them, someone hit him from behind and he collapsed.
Back at NCIS headquarters, Diona Reasonover’s character Kasie chose to complete the system reboot on a late Sunday night to avoid daytime disruptions. She believed the building would be empty and the work would go smoothly. But she was wrong. Someone broke into the headquarters while the mainframe was shut down for the midnight upgrade.
Kasie tried to keep the break-in a secret from her superiors, but Gary Cole’s Alden Parker and Brian Dietzen’s Jimmy Palmer soon learned about the problem. They discovered that one of the tech trolls Kasie was working with had disappeared. Later, they found Daryl, the missing tech troll, had been killed.
Sam Hanna Joins Parker Inside the Dark Headquarters
Parker began searching every room in the building to find the intruder. When he entered the multi-purpose room, he found Sam Hanna resting on a couch. Sam explained his connecting flight got delayed, so he decided to spend time at the NCIS headquarters for free instead of paying for a hotel room.
Sam had no idea about the reboot or the murder that had just happened. Parker asked him to help with the investigation, and Sam agreed to join the team. Their partnership gave viewers a preview of what to expect from the upcoming spin-off show NCIS: New York, which is scheduled to join CBS’ lineup in fall 2026.
The investigation led the team to question the tech trolls Kasie had brought in for the upgrade. Kasie had lied to them, saying Daryl had food poisoning and was taken for medical care. She believed none of the tech trolls were responsible, and her instincts turned out to be correct.
The real culprit turned out to be Tommy, the building’s janitor. Someone had taken Tommy’s family hostage and blackmailed him into plugging a drive into Kasie’s laptop during the reboot. The team caught him in the middle of the act. Tommy admitted he had no way out and was desperate to save his family.
The NCIS team arrested Tommy for Daryl’s murder. They also found the missing plumber and freed him. The hostage family was rescued. At first, the case seemed solved. But then Kasie made a disturbing discovery.
“I think I’m the reason why Daryl’s dead,” Kasie said after finding that an important program file called Edna had been stolen from her laptop.
Kasie’s Personal Connection to the Stolen Program
The episode ended with a rare To Be Continued message, confirming the story was not over. Kasie revealed that the program labeled Edna was something she created herself. Someone had gone through all the trouble of planning the break-in, taking a family hostage, and killing Daryl just to steal that specific file from her computer.
The episode gave Diona Reasonover’s character more screen time than usual, putting Kasie at the center of a deeply personal case. Some critics noted that Sam’s return overshadowed what could have been a stronger Kasie-focused hour, but the cliffhanger ending set up important questions for future episodes.
Brian Dietzen’s Jimmy Palmer also had several key moments in the episode. Sam encouraged Palmer to share his goal of climbing Mount Kilimanjaro with the rest of the team. Palmer also showed his physical training by climbing up an elevator shaft when the team got stuck between floors. Sam used reverse psychology to push Palmer into action, proving the medical examiner had more skills than he gave himself credit for.
The episode also included emotional moments where Parker and Sam talked about the death of Director Leon Vance, played by Rocky Carroll, who was killed in the line of duty during the 500th episode. Both characters admitted they were still processing the loss.
“Tell you what, we replace old MTAC with new MTAC, but people, like Vance…” Sam said. Parker replied, “No replacing that.”
Sam then shared that he had been thinking about his future and was done waiting to make a move. This conversation set up his transition to the NCIS: New York spin-off, where he will partner with Scott Caan’s character to lead a new team defending one of the most vital cities in the country.
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Where to Watch NCIS Season 23 Episode 17
NCIS Season 23 Episode 17 aired on Tuesday, April 21, 2026, at 8:00 PM Eastern Time on CBS. For viewers on the West Coast, the episode aired at 8:00 PM Pacific Time. Paramount+ Premium subscribers could watch the episode live as it aired. Paramount+ Essential subscribers could stream it the next day on April 22.
International viewers had different viewing times. In the United Kingdom, the episode became available on Wednesday, April 22, at around 1:00 AM GMT. Canadian viewers watched on Tuesday, April 21, at 8:00 PM ET on CBS or Global TV. Australian audiences could stream it on Wednesday, April 22, at around 11:00 AM AEDT on Paramount+ Australia. In India, the episode was available on Wednesday, April 22, at around 5:30 AM IST.
The next episode, titled Bad Impressions, will air on Tuesday, April 28, 2026, at 8:00 PM ET on CBS. The promo suggests the team will race to help one of their own who has been framed for murder.
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