Sally Harrison is a harassed, well-meaning but scatterbrained young widow doing her best to bring up two boisterous sons, Simon and Peter.
Sally packs Simon's bag for a camping trip to stop him making more lists, a test run in the garden leads to a sleepless night filled with fussing, and the children from next door pop round when Simon ends up catching a chill.
Simon reveals that he's been trying to save enough money to buy a bike, Sally takes on some extra hours so she can surprise him on his birthday, and hiding it proves to be as difficult as getting it home in the first place.
Offering to look after a mynah bird for a lady in need of an operation, Sally finds an empty cage, leaving her desperately looking for a replacement, and a pet shop owner confused by a list of very peculiar requirements.
Peter turns to Pythagoras when the family try their best to Spot the Ball, Sally asks Mr Campbell to lend her a car so she can have driving lessons, and Auntie's unimpressed when she picks up an old banger from a vicar.
Sally falls for Simon's teacher when she confronts him about his report, being invited to an art happening allows her to show her natural talent, and a date at a cocktail bar sees her get far too familiar with Tom Collins.
Sally's utterly horrified when Peter tells her that she's got a wobbly bum, the boys bet her that she won't be able to lose as much weight as Auntie, and things quickly get tough when hunger starts to get the better of her.
Sally panics when she wakes to the sound of strange voices in the house, Simon and Peter are told to find hobbies when television is banned, and Auntie gets a nasty shock when she tries to spy on a very secret project.
