BOSTON (CBS) — As Cameron Cook helped his little sister with some homework tonight, it was hard not to think about the little girl he protected from a pervert over the weekend.

The South End teen and his mom were doing some shopping at the South Bay Plaza Target when something odd caught his eye–a man with what he describes as a demonic look on his face.

“I seen the guy grabbing himself, and my mom goes, ‘Cam let’s go, keep walking,’ I was like, no, something’s going on.”

The 17-year-old noticed that man fixated on a young girl pushing a shopping cart.

“I was close enough that I could smell the liquor coming from his mouth,” said Cameron’s mother, Heather Cook. “It was horrible.”

But it got worse when the man thrust himself up against the somewhat startled youngster, prompting Cameron to step in.

“So I went up to him, I was like, ‘Excuse me sir, do you know her?’ And then the first thing he said was, ‘I’m not a pervert, I’m not a pervert.’ I was like, I didn’t ask you that sir,” said Cameron.

“He was big, and Cameron had no fear at all,” said his mother. “He just stood firm on the fact that he knew what this man was doing was wrong.”

Cameron suggested the man leave the store, and he did–denying and cursing all the way.

The store manager would later call to say that store surveillance video had been turned over to police.

“I’m very proud of him, but it’s totally within his character,” Heather Cook said. “He’s not afraid to do what’s right.”

There were also heartfelt thanks from the young victim’s mom, who apparently was in the bathroom at the time.

“I’m just happy I was there to protect her,” said Cameron. “Because you never know what could have went on.”

Heather Cook said the store manager told her that video showed the man climbing into a waiting car outside.

Police advise parents never to leave their small children alone in a store–take them to the bathroom with you.