In season one, Roy and Moss toil in the squalid basement of a huge company, fielding IT help-desk calls. Roy has a lousy attitude coupled with an eye for the ladies, while Moss is dressed by his mother and has an aerosol can of water clipped to his belt with which to spray his ear when it gets hot. Into their life of users, pizza, science fiction and firewalls comes middle manager Jen, a punky can-do career gal who doesn't know one end of laptop from the other.
Jen is hired as the manager Reynholm Industries although she doesn't know the first thing about computers.
Denholm declares war on stress and threatens to fire anyone who is under stress by the end of the day. Will the team hold it together by the end of the day so no one gets fired?
Love is in the air with the IT Crowd! Roy has a wonderful date, only to learn that he had something nasty on his forehead the whole time. Jen fancies the security guard and tries to impress him by guessing the answers to questions on classical music. Roy's decides that women only like bastards. Jen disagrees, so to settle the argument, Roy puts a fake profile up on an online dating site. Roy and Moss create a horrible online profile, only it works a little too well.
Moss learns that his new mug with his name on it has gone missing. Roy refuses to allow Jen to see what's behind the "red door" for fear that Jen will upset the delicate eco-balance of the office. But Roy and Moss go on an IT call, leaving the Red Door unguarded.
Jen has a date with Bill Crouse, and finds him really offensive. To help Jen avoid contact with Bill, Moss resorts to extreme lying which leads everyone to believe that Jen is dead! Meanwhile, Roy finds himself trying to escape the attentions of one of the "beautiful people" on the 5th floor.
Jen explains to Roy and Moss that her "Aunt Irma" is visiting. When they don't understand, she explains that she has very powerful mood swings around a certain time every month, which leads to Roy and Moss displaying the same symptoms. Project Iccarus is finished and all of the teams assemble before Denholm as he thanks everyone even remotely associated with the project - except for the IT Crowd. To retaliate in being left out of the the "thank you's," the IT Crowd decide to sabotage the celebration party only to find themselves enjoying in the festivities and to the bizarre conclusion the morning after. Will everyone be able to work together again?