Upton's dogged pursuit of a missing teenage girl leads the team into a dark web of human trafficking. Chief O'Neal becomes involved with the unit's investigation when it becomes evident his son, Sean, has a connection to the missing girl.

When actionable evidence finally surfaces against Sean O'Neal, Upton and the team work relentlessly to build a case in secret. They discover Sean is more elusive and dangerous than anticipated.

After a shocking discovery, the team begins closing in on Sean O’Neal with every shred of evidence they can find. Determined to keep his son out of prison, Chief O’Neal hires a lawyer.

Sean O'Neal surprises Upton with a call from prison, revealing sensitive information. Meanwhile, the team quickly mobilizes to stop a crime in progress before it's too late.