Red finds out that The Courier - a middle man that no one crosses - is delivering a package worth millions of dollars to an Iranian spy. Only the Courier is a ghost no one including Red, knows what he looks like. While racing to stop the mysterious criminal transaction, Liz , inadvertently finds herself thrust into a dangerous kidnapping plot. Meanwhile, Ressler must finally accept that Liz is a valuable asset to the team.

After a chemical attack on a subway, Liz and the FBI search for the man responsible. Liz reluctantly calls on Red for his help after she finds her search for the next person on the blacklist, brilliant scientist Frederick Barnes, heading to a dead end. Meanwhile, Liz wants nothing to do with Red after he implicated Tom.