Paul and Marsha have been married for three years and would like their own place. Murray and Diana are unmarried and also want their own place. However, neither couple can afford to buy on their own so it seems that the solution for both couples is to move in together.

Life should be bliss for Paul and Marsha now that they aren't living with his mother any more. However, she keeps coming round and trying to take over. Murray thinks he has a solution that can't fail.

Paul has always believed that a man should keep his promises, and after a drunken suggestion of wife swapping, Murray holds him to his word.

For a man who doesn't approve of gambling, Paul plays for high stakes. Meanwhile, Diana plays her own game in her efforts to get Murray down the aisle.

A computer is enlisted to help Paul prove that he's a better housewife than his wife. However, the computer can't explain Murray wearing a dress, or whether he is a thief.

Paul is so fed up with sharing with Murray he decides to sell his half of the house.

When friends with a baby visit, the girls get broody.

Murray and Paul have a bet the former can't give up smoking and the latter can't give up sex.

Murray has a lot of questions to answer — who does the dog belong to? Why is he anxious that everyone should leave? And most importantly, why is there a naked woman in the living room?

The couples buy a car which may or may not be stolen. Murray teaches Paul to drive.

The girls set up the men to test their fidelity.

When the television breaks, the two couples decide that they can live without it. However, it's not long before withdrawal sets in.

Murray always takes Diana for granted, something that Paul is quick to point out. When Giles appears, Murray realises that he has competition and he starts to change his ways — he even contemplates the ultimate sacrifice.

It's finally happened, Murray is about to make an honest woman of Diana but he's regretting one thing — making Paul the Best Man. His worst fears are confirmed when Paul insists on turning up for the wedding in his birthday suit.

When Paul suggests increasing the numbers in the family, Murray puts his and Diana's share of the house on the market. However, Paul is displeased with the potential buyers and Diana has something on her mind.

With the prospect of parenthood on the horizon for Murray, Paul is determined to steer him in to a proper job with a reliable income.

It's time for Diana's first prenatal check up and Paul is instructed to hold sex education lessons.

When an old schoolmate gets in touch with Marsha and Diana, they reluctantly invite her round. They know it may ruin Paul and Murray's Sunday afternoon but they couldn't say no to the 'plump old Pear Drop'.

When Paul's mother comes to stay, there's a feeling of gloom amongst the household. However, the arrival of Murray's father adds an unexpected twist.

Now that the birth of the little McCoy is imminent, Paul tries to sell their half of the house again.