Baby fever hits the Brown household as a pregnant Maria prepares for motherhood, and Agnes is keen to give her new daughter-in-law her unique brand of advice about raising children. Maria is grateful when Agnes offers to look after the robot baby she has brought home from her pre-natal class, but it turns out that Mrs Brown's babysitting techniques are not exactly orthodox. And Maria has some exciting news for the Brown family.

When Agnes's family start making comments about her weight, she decides to go on a diet, and quickly discovers just how difficult it is to overcome her craving for fish and chips. Cathy brings her new, older man home. He is a psychiatrist, and seems much more interested in Agnes than he does Cathy. Meanwhile, Rory has a professional dilemma when he discovers some illegal drugs at work.

Spartacus, the old family dog, is looking poorly. Reluctantly, the family decide the time has come to put her in a home. However, when the Brown children gather together to decide how to break the sad news to their mother, Agnes gets the wrong end of the stick. Under the impression that her children are planning on putting her in a nursing home, a furious Agnes sets out to persuade her children she is not going senile.

Agnes is disappointed with Cathy when she decides to get a boob job to impress her boyfriend, Professor Clowne. Agnes is also distinctly unimpressed with Buster when she meets the man he has hired to measure up her kitchen. Meanwhile, Professor Clowne has a life-changing proposal for Cathy - if he could only find the perfect moment to ask her his very important question.