NCIS: Hawai'i series finale ending explained: Did the team stop the Compound X?

It was rather abrupt how NCIS: Hawai'i season 3, one of the spinoffs of the famous CBS franchise, NCIS, came to a crashing stop with a recently announced cancelation, sending shockwaves even through the members of the cast. With no one expecting it, NCIS: Hawai'i had to settle for a season finale in place of its series finale on Monday, May 6.

Bringing forth a brilliant episode filled with drama, deceit, and standout heroes, this episode was perhaps as perfect as a suddenly canceled show could get to a satisfying ending. Building on the bioweapons, Compound X, the series finale delivered an adrenaline-filled chase that also featured some of the finest moments of Vanessa Lachey's Jane Tennant.

Season 3 of NCIS: Hawai'i, however, ended on a Marvel-esque cliffhanger, which seemed to hint at extending the universe, but fans will never get to see any more of the characters or the story. The story did end the ongoing arc about Compound X, which was also a key element of the previous episode, depicting how the team stopped it from spreading.

Here is what happened at the end of NCIS: Hawai'i season 3.

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NCIS: Hawai'i season 3 ended with a cliffhanger but also did everything right as a finale

Picking up from exactly where the previous episode left off, the season finale of NCIS: Hawai'i kicked off with Sam Hanna's (played by LL COOL J) group of elite agents stuck in a chemical plant. Annalise Cruz (Rachel Mars) got her hands on the terrifying Compound X, whose effects on the body were described in the latter part of the episode.

After the doctor unleashed a canister on Hanna's team, she ran away with four canisters of the deadly compound. Sam, in his desperation, tried to save the team, cracking his respirator shield in the process, which became a driving plot point for the rest of the episode.

Jesse Boone (Noah Mills) and Jane Tennant rushed to stop Dr. Cruz, who was making her way out of the chemical plant. She also injected herself with an antidote before leaving. Sam tried to chase Dr. Cruz but collapsed before he could reach her.

Back at the headquarters, Dr. Cruz's true identity was revealed as Talla Florez, an organic chemist from the Philippines. They also discovered that the plan that Florez has goes way beyond just hurting the NCIS agents, and may even be fatal for the entire country.

As they realized there was an antidote to the compound, Jesse went back to the lab to recover the antidote. Jane, meanwhile, figured out the location of Doctor Cruz and went to wait in the motel for her. What followed was one of Jane's peak moments in NCIS: Hawai'i as the team leader went to a great extent to interrogate Dr. Cruz after shooting her in the shoulder.

After a lengthy interrogation, which was motivated by Jane and the team's desire to find the antidote for Sam Hanna, they learned that Cruz's target was Hawai'i. The various CLA agents were about to go for the family members of important government officials, which the team stopped in an adrenaline-filled action sequence.

Back at the other end, Sam was almost dying when Carla injected an untested dose of antidote in a last bid to save him. By the end of the episode, Dr. Cruz escaped her captivity and held Carla at a scalpel point. But Sam Hanna recovered just in time to take her out for good, ending a brilliant saga of action and thrill.

But the episode ended on a steep cliffhanger as Maggie Shaw (Julie White), Tennant's mentor and frenemy appeared in her life. Sadly, this arc will see no ending. Perhaps, the entire NCIS: Hawai'i team celebrating the case and Hanna's recovery is as close as fans will get to a finale.

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All the episodes of NCIS: Hawai'i are now streaming on Paramount+.