"Hawaii Five-0" nemesis and serial arsonist Jason Duclair makes a fiery return. The team goes on a manhunt to catch Duclair and other escaped convicts, including Kono's husband, Adam. Will Adam return quietly or will the pull of freedom push him to cross a line?

Kono and Adam's relationship has been fraught with challenges and dangers since day 1. Despite it all, the two have remained strong and committed to their desire to live a normal life with each other. But Adam's escape will reportedly create even more problems for the embattled couple.

In episode 21 of "Hawaii Five-0" season 6, six dangerous inmates manage to escape after a dangerous chemical is deliberately spilled in prison. Among the inmates who will escape are Jason Duclair (Randy Couture) and Adam Noshimori (Ian Anthony Dale), Kono's (Grace Park) husband and former Mafia head.

An Instagram post by wrestler Couture shows him with Dale, the other escapees, and director Peter Weller.

Fans will recall that McGarrett (Alex O'Loughlin) and his team had several run-ins with Duclair and they already know how dangerous he is. The question now is who arranged for Duclair and the others to escape. While there's been speculation that Gabriel Waincroft (Christopher Sean) might be behind the escape, there's no indication that Chin Ho's (Daniel Dae Kim) former brother-in-law will be making an appearance this episode.

But what fans are no doubt wondering about is how this escape will affect Kono and Adam's relationship. Kono has reportedly told her team not to withhold information from her regarding the manhunt. It's also been said that "Five-0's" resident sniper is worried her husband might become desperate to return to prison that he might hurt or kill someone.

Duclair might be the main villain in episode 21, aptly titled "Ka Pono Ku'oko'a" or "The Cost of Freedom," but fans should prepare for a big Gabriel story arc as season 6 comes to a close. There have been reports that the two-hour finale will find the "Five-0" team pinned down in Oahu's Chinatown and protecting an injured Gabriel from gunmen who are looking to kill the criminal mastermind.

Chin Ho and the rest of the team protecting Gabriel certainly raises eyebrows, as he's been responsible for a lot of their problems this season. But the whole story will undoubtedly be revealed in an exciting way in the finale.

Episode 21 of "Hawaii Five-0" season 6 is set to be aired on Apr. 22, 9 p.m., on CBS.