Season 2

After enjoying a park performance of Schubert's Unfinished Symphony joyously with Catherine, Vincent discovers Rollie, a former resident of 'The World Below', once a gifted pianist who played the classics stunningly by ear, but now a drug addict struggling to survive in the city. Through a series of flashbacks, we learn Rollie feels responsible for the death of a helper who taught him to read music.

Catherine longs for Vincent to escort her to a secret hidden, childhood place in Connecticut. Yet Vincent realizes that there is too much danger if he were to venture above. He then begins having visions of an angel who takes him on a journey of what life would have been like if he had never existed with one of them having involved Paracelsus successfully taking over 'The World Below'.

Vincent rescues sailor Dimitri Benko from drowning and brings him to 'The World Below' to recuperate. Little does anyone know, Dimitri is carrying the pneumonic plague which soon becomes an epidemic amongst the residents of the tunnels and begins taking lives. Meanwhile, Catherine discovers that Dr. Peter Alcroft is an old friend of Father when it comes to helping the infected.

'The World Below' plans an annual winter event called Winterfest with Catherine and the other 'Helpers', unaware that Paracelsus schemes to crash the party. Catherine and Vincent suspect that someone at the party is actually Paracelsus in disguise.

Catherine convinces Vincent and Father to welcome pregnant former prostitute Lena to 'The World Below' where she can have her baby and be part of the community, but a crush on Vincent turns to more for Lena after her baby is born.

Deaf Laura Williams now lives in surface New York but backs away as a helper for 'The World Below' when she falls in with a gang of young, angry deaf people whose leader, Lincoln, is investigated for a security guard's murder. Laura's boyfriend in the gang, Jerry, is an undercover cop who reveals his secret to her, prompting her to run away.

Catherine befriends and takes in young Michael Richmond, who's lived in 'The World Below' since childhood but now begins college in the city. However, the revelation of his real parentage and a crush on Catherine drive him to second thoughts until Catherine and Vincent convince him to try again.

Brian, a D&D obsessed teen who lives in Catherine's apartment building, inadvertently discovers 'The World Below' while seeking refuge from his divorced parents' testy joint custody and following unsuspecting Catherine into the tunnels. The tunnel dwellers convince him to keep their secret while offering him a refuge if he wants it.

Devin Wells returns to 'The World Below' with Charles, a deformed man with Proteus syndrome who seeks sanctuary from his abusive brother while escaping from a carnival where he's billed 'The Dragon Man'. Vincent befriends Charles but the deformed man's fear and awkwardness lead to complications until Devin agrees to care for Charles at a mountain retreat.

A resident of 'The World Below' named Kanin—about to celebrate his first wedding anniversary below—is recognized by a woman in 'The World Above' as the driver who killed her small son in an accident sixteen years ago, the real reason Kanin retreated to the tunnels. Catherine inadvertently discovers his warrant and doesn't want to force Kanin to leave his family, but Vincent convinces him to face his responsibility and give closure to the grieving woman.

When a group of homeless people find their way into 'The World Below', Father decides to welcome them. Vincent is wary as it seems that the indigents are violent and disturbed.

When Catherine's father dies of a stroke, she retreats to 'The World Below' to grieve. She asks Vincent to let her stay with him and not return to 'The World Above' and though he agrees, he knows that eventually she will need to go back.

Former 'World Below' resident Lisa Campbell – now a world-famous ballerina — returns to the tunnels for refuge, desperate not to testify against her controlling and arms-running boyfriend. Her return unnerves Vincent—who loved her when they were young, but who injured her once during an embrace, a major reason he fears physical intimacy with Catherine. But Catherine consoles Vincent and convinces Lisa to face the authorities and do what she can to put her boyfriend away for his crimes.

Eccentric young artist Kristopher Gentian keeps appears in Catherine's life after meeting her in a bookstore—including near a tunnel entrance where he sees Vincent. Believing he faked his own death to advance his previously obscure works, Catherine tracks his paintings to a warehouse where Vincent joins her, but Kristopher vanishes after showing them the rest of his works.

On the night of their second anniversary, Catherine and Vincent are unnerved to think a stalker claims to have seen Vincent, which he reiterates in a frightening phone call to Catherine. Determined to learn his identify, but afraid to involve the police to protect Vincent, Catherine is abducted by the stalker while Vincent and Joe separately try to find her.

Catherine travels to California as part of an investigation for the New York office. She and Vincent discover just how strong their bond is when Vincent is able to warn her telepathically of an impending attack as she tries to bring a witness back with her.

Catherine and Joe are on a case involving a high-powered Wall Street celebrity whose child abuse resulted in the death of his son. Catherine is named prosecutor and she soon must deal with the challenge of trying to get the child's mother to testify against her husband.

The CIA pushes Catherine and Joe off investigating the murder of an old man who proves to be the father of Burch—whose shady dealings in Central America have put him in danger from a country's death squad, leading Catherine to put her own life on the line to help him.

Two rich kids have been targeting and murdering prostitutes for fun. Late one night, Vincent witnesses their latest murder but is unable to stop them. Catherine puts together a case against them but has a difficult time putting them away. Meanwhile, Vincent has set on his own to put an end to their crimes.

Catherine is attacked in rhe park by two men disguised as police officers. Vincent comes to her rescue, only for it to be a set-up created by a shadowy figure who has hired an investigative reporter named Bernie Spirko to expose Vincent's existence to the public at large.

In the aftermath of Spirko's death, Burch and Catherine set out to find the man who hired his killer—unaware the killer is Paracelsus, who fatally stabbed Spirko, setting in motion the next stage of his plan to take over 'The World Below'. Disguised as Father—whom he left bound and hidden in a rented penthouse—Paracelsus lies to Vincent about his birth, which brings Vincent to the verge of madness in a final confrontation.

Following Paracelsus's death, and Father's revelation of the truth about his abandonment and adoption, Vincent comes to terms that the beast within is causing him to lose control until Catherine daringly joins him to comfort him through it.