Little Croc wants a pet. But his mum and dad have other news - they are expecting a baby. And when Baby Doris arrives, Little Croc decides she is the most annoying little sister ever - she wakes him up in the night, she scribbles on his pictures and she spoils his favourite toys. But luckily Little Croc's older brother Boris is there to show Little Croc that being a big brother can actually be a lot of fun.