“NCIS: Hawai'i” Says Goodbye with Action-Packed Finale After Controversial Cancellation: How It Ended

The Vanessa Lachey-led procedural concluded after three seasons

NCIS: Hawai'i has taken it's final bow the only way it knows how — with a whole lot of action.

The final episode in season 3 of NCIS: Hawai'i , which aired Monday, May 6, became the show's series finale after the Vanessa Lachey-led procedural was canceled by CBS in April. The ending comes shortly after the franchise hit 1,000 total episodes last month.

In the episode, the island-based spinoff series picked up with Sam Hanna's (LL COOL J) group of elite agents in a chemical plant where Dr. Annalise Cruz infected them with Compound X, an odorless, airborne bioweapon that triggers the body to attack itself.

After Dr. Cruz unleashed a canister of Compound X on the agents and ran, Sam hurried to the air-locked room where his team was slowly dying of the virus. Determined to help his squad, Sam hurled his body on the steel door with so much force, that his respirator shield cracked. Soon, he became desperate and opened the door with an explosive, but was quickly stopped by one of the agents on his final breath.

Related: NCIS: Hawai'i Canceled at CBS After 3 Seasons and Franchise's 1,000-Episode Milestone

"No, you need to get away from here! You know I'm right," the agent gasped before collapsing on the ground.

Meanwhile, Jane Tennant (Lachey) and Jesse Boone (Noah Mills) raced to find Dr. Cruz before she left with the remaining four canisters of Compound X. Dr. Cruz quickly made her way out of the plant, but not before injecting herself with an antidote after getting exposed to the virus. Sam heard Dr. Cruz's commotion and chased her up a stairwell.

As he coughed and gasped for air, he promised to make her "answer for each one of those dead agents" and aimed to make an arrest before he fell backward.

"That's the virus, it's kind of amazing to experience right? Every weapon in your biology turning against you?" Dr. Cruz said before running off.

Related: Vanessa Lachey Teases Personal Connection to NCIS: Hawai'i Episode: It's 'Allowing Me a Lot of Healing' (Exclusive)

Back at the precinct, Alex Tarrant (Kai Holman), Ernie Malik (Jack Antoon) and Lucy Tara (Yasmine Al-Bustami) found out just how deadly Compound X can be. The virus triggered a "cytokine storm" with side effects including sweating, vomiting, blood, organ failure and death in minutes.

While telling Jane, Jesse and medical examiner Carla Chase (Seana Kofoed) how he got infected, Sam's condition helped the trio discover that Dr. Cruz possessed an antidote. At headquarters, Alex, Lucy and Kate Whistler (Tori Anderson) revealed Dr. Cruz's true identity as Talla Florez, an organic chemist from the Philippines involved with the "colonial liberation alliance," an organization that seeks to "eradicate" United States "imperialism" through "any means necessary."

As the team back in Hawai'i tried their best to nail Florez and the CLA's next target, Jesse headed back to the lab to search for another dose of the antivirus. While he was able to recover the antidote, he discovered the vials were crushed and returned to a converted veterinarian clinic where Sam was being isolated and treated.

Related: Vanessa Lachey Reflects on Becoming NCIS' 'First Female Lead' as the Franchise Hits 1000 Episodes (Exclusive)

With the help of Ernie and Lucy, Jane figured out Florez's location and waited for her in her motel room. Jane then put Florez in her place after shooting her in the shoulder and dragged her back to the vet clinic for interrogation where Carla discovered that there is only enough antivirus for one dose.

"I was able to extract enough of the antidote for maybe one dose," she said solemnly. "If we had the Compound X it would be [simple] but since we don't ... we need a sample of the antidote to synthesize more. It could be thousands of lives saved."

Carla revealed that creating an antidote could take hours or days "under these conditions," fully aware that Sam's clock was ticking. Jane then decided to take matters into her own hands and used unique methods to extract the location of the Compound X canisters from Florez. From threats of pulling teeth to using AI technology to tricking Florez into thinking her little sister was in NCIS custody, Jane finally learned that the CLA's next target is in Hawai'i.

Related: Vanessa Lachey Shares Stats of Now-Canceled NCIS: Hawai'i’s High-Viewership Ahead of Series Finale

When Sam's condition grew worse and he stopped breathing, Carla injected a rough untested dose of her antidote and he began to stabilize. Back in Hawai'i, the team figured out that the CLA intended to go after the family members of important government officials and tracked them to a hotel where a celebration was being held. Though Alex was able to track down three canisters of Compound X, the team scrambled to find the last can. Eventually, Lucy found a CLA agent posing as hotel security and after throwing punches, she finally secured the missing canister by eliminating the enemy agent.

In Serbia, Florez escaped her bounds and threatened to hurt Carla by holding a scalpel to her neck. Her efforts were stopped when Sam shot her dead after emerging from his hospital bed.

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After making a full recovery, Jane led Sam to his surprise party where he made a touching toast to the team for all of their efforts and well wishes.

"When I first arrived on the Island, I think some of you may have been wary," he shared. (The actor joined the spinoff at the beginning of the season after spending 14 seasons on NCIS: Los Angeles.) "But thanks to your boss Jane Tennant, that didn't last long and I'm truly honored to be thought of as part of your o'hana and thank you all from the bottom of my heart."

"And to those who didn't make it. We will never forget your sacrifice and we'll always be in your debt," Jane added, before she led the team in a toast, "Okole maluna!"

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