I was in Polaris. The guy was in coach. He kept coming up to Polaris during the initial drink service. Flight attendant told him to return to his seat. He walked back but then a few moments later, he's back up in the Business cabin. He appeared to be under the influence of something. Then the puraer told the entire cabin to return to their seats. He didn't comply. Then restrained him & returned to SFO. We are now waiting for a new crew & the plane to be refreshed.