Six dangerous prison inmates escape after a chemical spill in the upcoming episode 21, titled "Ka Pono Ku'oko'a," of the sixth season of the action police procedural drama "Hawaii Five-0."

The Five-0 team is on a manhunt after six prisoners are able to escape. It happened after someone intentionally caused a chemical spill. One of the inmates who got away is Kono's husband Adam.

The promo trailer for "Ka Pono Ku'oko'a" shows Kono learning the bad news that his husband is among the six prison inmates who escaped following a deliberate chemical spill. She even thinks that his husband is not going to stop getting away until he kills one of the prisoners. She also tells her team that they don't need to lie to her. She wants to know whatever happens to the manhunt.

In other related news, Abby (Julie Benz) shared to TV Line how it's like to keep a secret — that she's the mole planted in McGarrett's team — from her cast mates.

She said that it was a terrible feeling to keep such a huge secret from everyone. She explained that the secrecy was because the producers wanted to put some shots of him and her character's love interest Chin. She explained, "[They want] the audience to interpret it in the moment as 'Abby's falling in love with him,' but in hindsight as 'She's observing him.' So if you go back and watch the previous episodes, you'll see some weird shots where I'm just staring at him."

Meanwhile, here is the recap of the previous episode, titled "Ka Haunaele."

The team Five-0 were tasked to investigate the stealing of a high-tech, indestructible suit that is created for special purposes in the U.S. military. Meanwhile, Jerry tried his best to help his sister rescue a captive elephant.

"Hawaii Five-0" season 6 airs every Friday at 9 p.m. on CBS.