Steve McGarrett and Detective Danny 'Danno' Williams pursue an expert hacker and are taken hostage by an escaped convict who convinces them of his innocence while the danger of Kono's relationship with the son of a Yakuza boss escalates. Chin Ho is investigated by Internal Affairs about his ties to the head of a drug cartel, and Catherine gains a spot on the team but must repay a debt of honor in Afghanistan. Joining the team this season is Captain Lou Grover to head the SWAT unit on the island.