Hawaii Five-0's investigators will encounter a master liar in "Ike Hānau (Instinct)," a maestro of deception who appears to have the whole team fooled. Well, everyone except Lou Grover.

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An old police academy buddy of Grover's (Chi McBride) will drop by paradise this Friday, but it won't be good times and laughs for the former classmates. Instead, Clay Maxwell's (Mykelti Williamson) wife will take a nosedive off a cliff, leading Grover to believe that Maxwell is really the killer.

A lack of motive and evidence, however, will have McGarrett (Alex O'Loughlin), Chin (Daniel Dae Kim), and Kono (Grace Park) scratching their heads. Find out how Grover will convince the team to take down the seemingly innocent cop in the clip below.

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While McGarret and Co. follow Grover's lead, Danny (Scott Caan) will have a few problems of his own. After being MIA for "Kahania (Close Shave)," the detective will spend episode 20 in tight quarters with Dr. Mindy Shaw (Amanda Setton) and a dead body. Elevators always get stuck at the most inopportune moment.

Find out more when Hawaii Five-0 airs Fridays at 9 p.m. ET on CBS.

Tags: Hawaii Five-O television CBS