The return of Hawaii Five-0's Catherine Rollins will unleash a new side of Danno.

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The detective has plenty of problems of his own - surprise son, anyone? - but alarm bells will go of for Danny Williams (Scott Caan) as Steve McGarrett (Alex O'Loughlin) and Cath (Michelle Borth) debate rekindling their relationship. Having already seen McGarrett get his heart broken once, Danno will be loath to let it happen again.

"[After Kono's wedding] Danny shows concern for McGarrett regarding Catherine's return to the island," CBS teased in regards to the premiere.

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With the McRollins ship set to take a surprising turn in episode 3, viewers can expect the opening episodes to be McDanno heavy.

"I can't get into specifics, but I have it on good authority that there are some very sweet and 'bromantic' moments on tap for Season 6, especially in the first three episodes," TV Line's Matt Mitcovich reported. "Danny is very much going to have McGarrett's back, I hear, maybe even being a bit protective of his partner in crimesolving."

Find out more when Hawaii Five-0 returns to CBS on Sept. 25 at 9 p.m. ET.

Tags: Hawaii Five-O television CBS