When his daughter turned 12, Gighe Dutta decided this would be the year that he and his wife quit cutting sugar cane in the fields of western India. The work required a long migration, and his daughter would have to drop out of school — the first step for many girls on a lifelong path of abuse and poverty.

But his employer refused to let them quit. He and his friends beat up Mr. Dutta and forced him into a car, Mr. Dutta said. According to a report that he filed with a local government agency, the men drove him to a mill that says it supplies sugar to many international companies.

Mr. Dutta was locked there for two days, he said, and left to sleep on the floor to reconsider his decision.

The sugar-rich state of Maharashtra supplies companies like Coca-Cola, Pepsico and Unilever. Local politicians and sugar barons say that laborers like the Duttas are free to leave. The work is hard, they concede, but laborers can always seek work elsewhere.

But the sugar workers of Maharashtra are far from free. With no written contracts, they are at the mercy of their employers to decide when they may leave. They frequently work under the threat of violence, abduction and murder.

There is no official data about how often such treatment occurs, and abuses often go unreported because workers fear retaliation. But workers’ rights groups, local government authorities, experts and even some mill owners say that kidnapping is not uncommon and that workers have little recourse.