'Magnum P.I.' Sneak Peek: Magnum and Higgins Argue Over Marriage (Exclusive)

Not everyone gets a happy ending.

Sometimes marriage isn't all it's cracked up to be.

On Friday's episode of Magnum P.I., titled "'Til Death," Thomas Magnum (Jay Hernandez) and Juliet Higgins (Perdita Weeks) are hired by an anxious groom, Aiden (played by Pretty Little Liars alum Ian Harding), who asks them to look into his bride-to-be on the eve of their wedding. What Magnum and Higgins believe is a simple case of cold feet turns into a web of lies and a life-or-death situation for Higgins.

In ET's exclusive sneak peek, Magnum and Higgins are tailing Serena, but Higgins is not keen on the case as a whole. "What's the opposite of 'time flies when you're having fun'?" she asks Magnum, prompting him to ask if their client and the pseudo investigation is boring her.

"Well, Serena's done nothing but wedding errands all day. We're cruising around burning petrol," she snarls. "And no, it's not meditative, Magnum. It's mind-numbing."

"Yeah, a lot goes into planning a wedding," Magnum replies, "which may come as a surprise to you because you didn't really pull your weight when we planned ours" -- a reference to their quickie engagement so Higgins could remain in the States and receive a green card. (They never did tie the knot.)

"You might be walking that plank real soon so I would take notes if I were you," Magnum says, implying that Higgins' relationship with Ethan (Jay Ali), who's in Kenya at the moment, may be headed down that path. Higgins, however, tells him to slow his roll on that front. Maybe an exchanging of vows isn't in the cards for them, as she talks through all the evidence they have yet to find to implicate Serena as a guilty party, still a bit wary that the bride is 100 percent innocent.

"Or there's nothing to find," Magnum says. "These two get married and live happily ever after."

But Higgins scoffs at the idea. "Oh please... this wedding is a rush job and the groom, whether he wants to admit it, has some rightfully cold feet," she argues. "Not everyone gets a happy ending."

Magnum P.I. airs Fridays at 9 p.m. ET/PT on CBS. For more, watch below.

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