Angela Rance suspects a demonic presence has entered her home, and enlists the help of Father Tomas Ortega, who calls on experienced exorcist Father Marcus Keane.
When 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.
Angela grows restless as her daughter's condition continues to deteriorate, and the demon turns its attention toward innocent victims. While Father Tomas is paid a visit by a familiar face from his past, Marcus journeys to an unexpected destination and receives guidance from a most unlikely source. With time quickly running out, the two priests must decide whether to defy the church by performing an unsanctioned exorcism.
The exorcism begins. As the storm of the century descends upon Chicago, Father Tomas and Marcus engage the demon in spiritual warfare. But the demon is ready and waiting with a few secrets of its own. Meanwhile, the demon's manipulations slowly begin to drive a wedge between members of the Rance family. Loyalties will be tested and lives will be forever changed.
The Rance family is engulfed in a firestorm of publicity after the media learns about the possession of Casey Rance. As Casey's story continues to make national headlines, Father Tomas finds himself unexpectedly thrust into the public spotlight. Meanwhile, Father Bennett attends a papal planning gala at Maria Walters' mansion, where members of high society gather to discuss the presence of angels in everyday life, and Marcus' search for answers leads him into the terrifying underbelly of the city.
With no sign of their missing daughter, the Rance family begins to disintegrate; Marcus looks to Mother Bernadette for help with the latest problem; news of Casey's possession goes public and Father Bennett continues his probe into Tattersal.
As Marcus, Tomas and Mother Bernadette race against time to defeat the demon, the Rance family finds itself drawn into the conflict. With the Pope's visit only days away, the church's enemies take aggressive new moves. Angela confronts a familiar face from her past, and Kat considers a new future.
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.
Season Finale. Everything has led to this moment. Forty years ago, the demon was denied its prize. Now it will stop at nothing to destroy Angela Rance and her family. Their only hope lies in two men: Marcus and Tomas. But with the enemies of the church mobilizing against Pope Sebastian, time is running out for everyone.
Season two picks up six months after leaving Chicago with Father Tomas continuing his training to become an exorcist under the watchful eye of his partner Marcus Keane. Their travels lead them to a troubled young woman in rural Montana, where their investigation puts them in the crosshairs of her extended family. But as Tomas' skills continue to grow, Marcus begins to worry that his apprentice is taking unnecessary risks. The action then switches to a secluded private island off the coast of Seattle, where Andy Kim runs a group home for at-risk foster children, whose lives are disrupted when the state sends a social worker to determine whether the foster home should be closed. Little do they know the true danger is yet to come: a malevolent presence that has set its sights upon one of the children in Andy's care.
Tomas and Marcus attempt to escape the custody of Cindy's enraged family, while simultaneously trying to finish her exorcism. Rose conducts her inspection of Andy Kim's household and is concerned about Caleb's mental state. Meanwhile, Andy's neighbors offer to teach the children farming skills, but there's something sinister behind their intentions. Additionally, Verity may be hiding something from the rest of her foster family. Then, Father Bennett tries to warn the Office of Exorcism of a new threat, but finds his attempts railroaded by menacing forces.
The situation at the foster home continues to deteriorate, as Andy tries to help his foster daughter, Grace overcome her agoraphobia. Meanwhile, Marcus and Tomas travel to Seattle where they encounter a new possession case, discovering a young girl who has been targeted by a force of pure evil. Father Bennett tracks down a rogue church operative named Mouse who is waging a one-woman crusade against the demonic conspiracy.
As Andy confronts the strange incidents taking place on the island, his foster home receives a surprising new addition. Marcus investigates a series of natural disturbances with the help of a local wildlife biologist, while Tomas continues to question the strange visions that led him to Seattle. Meanwhile, Bennett's uneasy partnership with the enigmatic Mouse takes a dark turn.
As Tomas and Marcus continue to investigate the strange incidents at the foster home, the demon finally makes its presence known. The two priests must race against the clock to find evidence of possession before it is too late. Meanwhile, Andy and Rose take the children on an overnight camping trip, setting them on a collision course with the supernatural presence on the island. Back in Rome, Father Bennett's uneasy partnership with Mouse takes a turn as disturbing new information about the conspiracy comes to light.
A visit to the foster home carries deadly consequences, as Marcus and Father Tomas attempt to draw the demon out of hiding. Rose finds herself the target of the demon's wrath. And no one suspects that a new danger may be lurking in the woods, waiting for its moment to strike. Meanwhile, Father Bennett and Mouse take the fight directly to the conspiracy as they attempt to hunt down an old adversary.
As the exorcism begins, the fate of the foster home hangs in the balance. This is an adversary unlike anything Marcus and Tomas have ever faced, and in order to save this family, the two of them must journey into the mouth of madness itself.
As Father Bennett and Mouse head west to rendezvous with Marcus and Tomas, new details about Mouse's tragic past comes to light. With time running out to finish the exorcism, one of the foster children is faced with a difficult choice. But the demon has other plans.
As the exorcism reaches a critical juncture, Tomas engages the demon in a desperate battle to save Andy's soul. Meanwhile, Marcus and Rose attempt to get the foster children off the island, but the demon has other plans. As the storm of the century descends upon the island, salvation may come from an unlikely source.
Season Finale. Everything has led to this moment. As one priest fights for his life in the hospital, another is forced to confront the ghosts of his past. With time running out to save Andy's life, one of the exorcists must make the ultimate sacrifice.
