After a two-year absence from the islands, Steve McGarrett returns to Oʻahu under the radar, drawn back by whispers of a shadowy organization known only as The Black Tide. This elusive syndicate has infiltrated every corner of Hawaii’s underworld—drugs, weapons, human trafficking—and their influence reaches deep into political and corporate power. The Five-0 Task Force has changed in his absence: Danny “Danno” Williams now leads the unit with a more cautious hand, Junior Reigns has stepped into the role of field commander, and Tani Rey has grown into a fierce investigator with her own network of informants. But the moment McGarrett walks into HQ, old bonds reignite—and so do old dangers.
The season begins with a chilling case: a series of high-profile assassinations, each staged to look like an accident, but connected through a coded symbol carved at every scene. As the Five-0 team investigates, they realize these killings are not random—they’re messages, part of The Black Tide’s plan to dismantle Hawaii’s law enforcement from the inside out. Their prime suspect is a mysterious figure called Ka Moana, a ghost from McGarrett’s Navy SEAL past who was presumed dead during a classified mission. The deeper they dig, the more McGarrett is forced to confront secrets he’s kept buried—even from his team.
Mid-season, the tension escalates when The Black Tide launches an all-out assault on the task force. Safehouses are compromised, allies are targeted, and Danny’s family is put in mortal danger. A shocking betrayal from within their own ranks forces the team to go rogue, abandoning their official badges to wage a covert war across the islands. From high-speed chases along the H-1 freeway to underwater firefights in coral caves, the season pushes the Five-0 crew to their physical and emotional limits. Every victory comes at a cost, and each loss fuels their determination to end the threat once and for all.
In the explosive season finale, McGarrett and Danny track Ka Moana to an abandoned sugar mill, where The Black Tide is preparing a shipment of chemical weapons bound for the mainland. The showdown is brutal and personal—bullets and fists flying through the smoke of collapsing walls. When the dust settles, Ka Moana is dead, but The Black Tide’s leader remains in the shadows, watching. McGarrett, standing on the edge of the ocean, realizes their war has only begun. As the waves crash against the shore, Danny joins him, and they share a silent promise: no matter how deep the tide runs, Hawaii Five-0 will be there to stop it.
