Brad Armacost

Lieutenant Severide (Taylor Kinney) is anxious to implicate the serial arsonist, while Dawson (Monica Raymund) and Shay (Lauren German) get a shock on a routine call. Meanwhile, suspicions continue to point to Clarke (guest star Jeff Hephner) as the mole inside the firehouse and Molly's falls deeper into the red. Elsewhere, Mouch (Christian Stolte) campaigns for union president, with the aid of Isabella (guest star Mena Suvari), and Boden (Eamonn Walker) butts heads with Gail McLeod (guest star Michelle Forbes).

While Bishop Egan denies Tomas permission to perform the exorcism on Angela’s daughter, Father Marcus breaks out of Saint Aquinas and joins forces with Tomas, though he urges him to get his ex, Jessica, out of his life and heart. The Rance family’s relationship with the demon deepens and when Marcus catches Angela stealing holy water, he instructs her on how to use it. On Chicago’s South Side, a series of bizarre ritual killings begin taking place.

Kat struggles to confront the realization that her friend, Julia, is dead. Shopping for a dress to wear to Julia’s memorial service, Casey is given a sexy, expensive and slightly inappropriate dress by a salesman at the store. Seeking permission to conduct an exorcism, Marcus and Tomas take footage from the Rance home to papal emissaries, only to be met with shocking news that will change Marcus' life forever.

The Rance family begins to disintegrate as days pass without any sign of their missing daughter. Marcus enlists the aid of Mother Bernadette to help him with his latest problem, Tomas finds himself snared in a web of lies after news of Casey's possession becomes public knowledge and Father Bennett's investigations into the mysterious Tattersal corporation lead him directly into danger.

On the eve of Pope Sebastian's visit to Chicago, Marcus and his companions race to avert a potential tragedy. Tomas is offered a life-changing opportunity, but will the sins of the past endanger his future within the church -- Meanwhile, as the Rance family attempts to recover from their most recent ordeal, a new problem threatens to tear them apart.