Russ is an extreme hoarder. He has completely filled up his apartment, forcing him to sleep outside. He's also afraid that the Fire Department will come to his house and he won't be able to clean enough in time to pass inspection. If this happens, Russ fears he'll become homeless. Meanwhile, Karen is plagued by her obsessive thoughts about death. She is constantly afraid that either she or someone she loves will die in an earthquake, in a car accident, or be brutally attacked.

Shannon is a hypochondriac with an intense fear of death. She avoids driving on the freeway for fear she'll spontaneously combust or go blind. Through CBT, Shannon will try to overcome her dread of driving so she can take her autistic child to a ranch for kids with special needs. Meanwhile, Todd has an obsessive compulsion to pull out his own hair. He spends his days writing obsessive thoughts on the walls and pulling hairs off his face and head. CBT is his last hope.

Traci struggles with both germaphobia and claustrophobia. She is constantly cleaning and is frightened to get on an elevator. She can't even enjoy home-cooked meals without fearing illness. Meanwhile, Judi is a hoarder. Losing her father at an early age, getting divorced, and having her only son leave home have caused an emptiness in her life that she tries to fill by accumulating piles of clutter.

Christa's OCD prevents her from eating most foods for fear they are contaminated. To ease her anxiety, she spends hours in front of the mirror with a pair of tweezers ruthlessly tearing into her skin, mostly her face. She is completely reliant upon her fiancé Shawn, but he doesn't know how much more he can take. Meanwhile, Ryan feels like a slave to his OCD rituals of checking, tapping, and counting. His morning routine is riddled with grooming rituals around showering, getting ready, and leaving the house. He even makes his pregnant wife participate in his compulsions.

Marie is obsessed with the weight of objects. She's afraid that the things in her apartment are getting too heavy, that the floor is weakening, and that the building will collapse, crushing her and her daughter. Meanwhile, Matt is agoraphobic with severe panic disorder. He's built his life around a "safe zone," which is near his home. When he drives, he fears that he won't be able to get back to his safe zone fast enough.

AJ needs a service dog, Sparky, to help manage her anxiety and panic attacks but she can't stop her OCD mind from bombarding her with horrific images of animal abuse. She also compulsively tweezes out her eyebrows to cope. Meanwhile, Vanessa has a compulsion to pick her skin and, at one time, she actually picked clear through to her jawbone. Vanessa recently connected with a woman online, and she's preparing to meet her new girlfriend for the first time.

Richie is an extreme hoarder who can't throw away anything that belongs to his deceased mother. As he grieves her loss, he's even blocked off the hallway to his mother's bedroom. In the longest therapy process of the entire season (approximately one year), his therapist pushes and helps Richie as he tries to fight through his emotions.