Catherine's pain about her fragmented life almost causes her to end her relationship with Vincent.

A stress-aggravated illness triggers Vincent's collapse. Vincent goes far back through the catacombs of the tunnels to hide in a cave. While in there he continually growls and thrashes about as if he's gone mad. Catherine goes after him because she says that she can't stand to see him like that. After all he is the love of her life.

Dimitri, a Russian sailor unknowingly brings the plague below.

Michael leaves to the tunnels to go to college above. Vincent deals with jealousy issues of not being able to go to college above. Catherine befriends him and helps him settle in. Michael eventually falls for Catherine and winds up kissing her. Then he is afraid of what Vincent will do when he finds out about the kiss.

Catherine's father dies and Vincent allows her to come below to grieve. He also makes her go back above because he knows that she does not belong there no matter how he feels. Catherine finally agrees and goes back above.

Catherine is harrassed by a peeping tom. The worst part is that this man has seen Vincent!

An insistent reporter sets off Vincent's confrontation with himself.

Catherine meets a strange man who says that he is an artist. His name is Kristopher Gentian. But when strange things begin to happen it leads both Vincent and Catherine to wonder if the man is really an artist or a ghost.

Elliot Birch is pursued by a death squad. Catherine puts her own life on the line to help him.

Catherine must travel to L.A. for information about a murder case. Even this far away, Vincent still has a sense of her. But because she is so far away there is nothing that Vincent can do if she does encounter danger. On the flight home Catherine remembers special moments with Vincent.

Vincent alerts Catherine to possible wrong-doing at a well-known, renowned orphanage.

Laura, a deaf-mute tunnel dweller, witnesses the murder of a police officer, for which another man is framed.

Attempting to aid an injured child (Eric) in the Maze, a cave-in traps Vincent and Father. Catherine, after facing Elliott Burch, who has agreed to be a witness against an extortionist, senses something is wrong and rushes to the tunnels.

Paracelsus, a former friend of Father's, sells an hallucinatory drug in the world above.

Steven Bass, Catherine's ex-fiancé resurfaces, and is behaving oddly.

Construction of the Birch tower is causing many problems in the tunnels. To help the problems stop Catherine agrees to marry Elliot Birch.

Winterfest is a celebration of great importance to those who live below. This is Catherine's first Winterfest. But this year Winterfest is interrupted by Paracelsus.

Paracelsus' lie about Vincent's birth brings Vincent to the verge of madness.

Vincent's foster brother, who is also Father's son, Devin, returns to the tunnels after a 20 year absence.

Paracelsus kidnaps Catherine, which causes Vincent to begin a quest to rescue her.

Devin, rescues a man who has elephant man's syndrome from a cruel circus man. The owner leaves the poor man locked in a cage like an animal. Devin, then brings him below where he knows that he will be safe.

Catherine must turn in Kanin. He is a tunnel dweller who is wanted for a past DWI vehicular homecide.

A murderous "family" takes up residence in the tunnels.

Vincent is captured and held hostage by two scientists who stick him in a cage. Catherine considers a new job in Providence.

While walking above one night Vincent spots an ex-tunnel dweller, named Rolly. Catherine and Vincent try to help him. Rolly is also a piano prodigy or at least he used to be. Now he's a junkie. Catherine and Vincent attend a concert in the park from below. In the middle of the concert a rainstorm begins. Vincent tries to cover Catherine with his cape but she pushes it off and allow herself to get soaked. Vincent watches in amusement. After Catherine is soaking wet she crawls back over to Vincent and collapses laughingly into his lap.