This crazy series begins when Janet Wood and Chrissy Snow, two attractive women, have a going away party for their roommate, Eleanor (who we'll meet in Episode 44). While trying to find someone to share the rent with, they find party crasher Jack Tripper in their bathtub. They have their doubts at first but when they find out that Jack is the only one that can cook (by going to cooking school), they want him to stay. The hardest part of this is trying to convince the landlords, Stanley and Helen Roper, that Jack is indeed good company. Stanley doesn't like the idea of a man living with two women, knowing what can go on behind closed doors. Jack pretends he is gay so that he can have a place to live. It works, and the rest is sitcom history.

Jack is all set to move into Eleanor's room, until Chrissy's mother unexpectedly shows up. Chrissy's mom does not know that she and Janet live with a man, so she tries to keep them out of sight. Janet and Jack go to the Regal Beagle to hide out, and Mrs. Roper finds out that Jack is not really gay. She manages to keep it secret from Mr. Roper.

Mr. Roper sets Jack up with his niece, who turns out to be very promiscuous in her way. Jack finds out that Mr. Roper set him up in order to turn him straight, and if he is, out he goes.

Larry Dallas, a slick car salesman, unloads a puppy on the trio. Knowing that Stanley doesn't allow pets, they try to hide it. The puppy is necesary for Chrissy's sleepwalking problem.

Jack's masculinity is put to the test when a big bully tries to have his way with the girls.

Oh my! The trio's rent money is missing and they scramble to get more money so Stanley will not kick them out. Unbeknownst to them, Stanley picked up the money earlier that day.

After Jack and Chrissy disturb Janet's time alone with her date, the trio agree to arrange reservation times for the apartment. However, Jack has an offer he can't refuse and he tries to renege on the agreement.

In order to earn tuition money, Jack takes on a variety of odd jobs, including an encyclopedia salesman and a nude model in a magazine layout.

Janet's co-worker Chloe gets a promotion after only being hired for a couple of weeks. Janet's upset because chloe got the job because of her looks not her skills.

Chrissy's new man is married, but she thinks he's single, and now her friends must prove to her the truth.

Jack must help Chrissy regain her confidence in her sex appeal, since he's the one who made her lose confidence after failing to come on to her when they spend a night alone in the apartment.