California's marijuana business is worth billions, but it's largely an illegal industry. And as it operates underground, human trafficking linked to it is booming.

>> Read more trending stories 

"None of this is monitored," a marijuana trimmer told Reveal. "No one's going to know you're here or not here. It's easy to go missing, I guess. It's easy for bad people to take advantage."

In Humboldt county, 352 people were reported missing in 2015. That's more missing people per capita than any other county in California.

The marijuana industry attracts a lot of young workers. Many of them have stories of abuse at businesses operating outside the law. Legalizing marijuana could help bring the industry out of the shadows. Californians vote on the issue in November.