Scott Caan Scott Caan

Book 'em ... into surgery.

Hawaii Five-0's Scott Caan aggravated an old knee injury and was flown back to Los Angeles for surgery on his ACL, a rep for the series said.

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Caan, who plays Detective Danny "Danno" Williams, is scheduled to return to the set Monday. Production will continue without him, though he will not miss an episode.

The 33-year-old actor's injury will be written into the show. Danny will be taken to the doctor's office following a mishap on the job. When the doctor asks whether anything traumatic has happened lately, Danny replies that he's got a new partner, Alex O'Loughlin's Steve McGarrett. "This guy is a physical injury!"

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"Working with McGarrett, you're bound to get a few bumps and bruises along the way," executive producer Peter Lenkov said.

Hawaii Five-0 is scheduled to premiere Monday, Sept. 20 at 10/9c on CBS.