'Hawaii Five-0' season 7 episode 8 spoilers: Terrorists seize winter formal; Danny and Grover discover Grace's secret boyfriend

Terrorists hostage people during a winter formal event in the upcoming episode of CBS' hit procedural drama "Hawaii Five-0" season 7.
Titled "Hana Komo Pae (Rite of Passage)," next week's episode will see an intense hostage situation. According to the official synopsis for episode 8, Danny (Scott Caan) chaperones Grace's (Teilor Grubbs) winter formal, but things will take an unexpected turn when terrorists arrive at the event. The group of terrorists seize the venue and holds everyone inside hostage in an attempt to kidnap a diplomat's son. Also, Danny and Grover (Chi McBride) are both surprised when they learn that Grace's secret boyfriend is actually Will (Chosen Jacobs).
Last week's "Hawaii Five-0" featured the show's milestone 150th episode, which centered on the kidnapping of Steve's (Alex O'Loughlin) mother. Steve was having a dinner date at home with Lynn (Sarah Carter) when Catherine (Michelle Borth) stormed into the house to tell her ex that Doris (Christine Lahti) had been kidnapped and imprisoned at a CIA black site in Morocco. While McGarrett was busy preparing for a rescue mission, Catherine had an awkward conversation with Lynn, who told her that Steve was actually planning to propose to her before she left him last season.
Speaking with TV Line, O'Loughlin explained that Steve pushed Catherine to say what her answer might have been for an important reason.
"As far as I'm concerned, he was just curious," the actor explained, "because for him to get serious with anyone else —really serious, if that's what happens—he needs closure on [Catherine], and [hearing her answer] gives him that closure. He's like, 'OK. How ironic. I guess this just wasn't in the cards,' you know."
Keep tuning in to all-new episodes of "Hawaii Five-0" season 7 every Friday night at 9 p.m. ET on CBS.