FBI child specialist Claire Bennigan investigates when kids are persuaded to play dangerous games.

As John pursues his mission, Claire looks into his identity. Drill keeps playing a dangerous game.

John Doe holds Dr. Maria Benavidez hostage as an unknown entity continues to blindly lead him to an undisclosed location, and Claire and Wes further their investigation into John Doe’s past whereabouts and begin to uncover what his next target is.

While Minx tries to persuade a disillusioned Henry to play one more game for Drill, the race is on for Claire and Wes to thwart John Doe from causing a major incident that could potentially kill millions of people.

Claire speaks with Sean, who has no memories of her or their life together, and tries to get him to remember something…anything about his past; Wes has an epiphany and heads back to Mali to take another look at the fulgurite, and Lena keeps a watchful eye on Minx to make sure that her conversations with Drill have ceased.

An astonishing breakthrough is made about Drill while Claire gathers together and talks to a group of children who have been contacted by it, and Wes makes a chilling discovery about Drill’s possible mission.

While Wes meets with the President of the United States to discuss what his team has discovered about the mysterious rock - and whether or not it should be destroyed - Drill sets his sights on a member of the President's family. Meanwhile, Sean reunites with his family, but the reunion could be short-lived as he faces a possible prison sentence for his collaboration with Drill, and Lena attempts to communicate with Drill, with the help of daughter Minx.

Claire and Sean track down a man who had his own deadly encounter with Drill — over 30 years ago.

Claire, Sean, Wes and Lena attempt to unravel the past of a man who first encountered Drill over 30 years ago, which could lead to a way to kill it -- before Drill finds a way to murder the man first.

A plan is put into place to trap Drill and attempt to drain away its energy, thus killing it in the process. But if unsuccessful, Drill could seek retribution in a most deadly way.

Thinking they might actually be able to defeat this unseen foe, Wes convinces the President to let him round up all of the children in a protected zone in the hopes that Drill will weaken.

One of the children is taken over by Drill, but not everyone is sure which one it is, leading to confusion and fear.

Season Finale- Drill’s mysterious end game is put into motion and the team must do their utmost to stop it before it reaches its final – and possibly deadly – conclusion,