Thousands of office janitors work at night, alone, sweeping up the crumbs from our sandwiches, taking out the garbage and scrubbing bathrooms. Many are immigrants – some undocumented – and many are women. With these conditions, they are particularly vulnerable to sexual violence.

In this segment, we hear from members of a tiny nonprofit who try to root out abuses in the cleaning industry; women who’ve sued janitorial companies for failing to protect them from rape and harassment; and an accused rapist who has run his own cleaning company.

This story is a part of a collaborative 18-month investigation with FRONTLINE, Univision, the Investigative Reporting Program at the UC Berkeley Graduate School of Journalism and KQED.