College student Katherine signs up to an internship programme which enables her to work at a marine animal rehabilitation centre in Florida, and stay with a host family, the Meres. When she meets them at the airport she is delighted to be with a real family as she never had one of her own, having spent her earlier years with uncaring foster parents. She is given a warm welcome by Lee and Alice Mere, and their daughters, Sarah, Talie and Chrys. When asked by 11-year-old Sarah to play dolls when they get home, Katherine admits she doesn't know how, as she never had toys of her own as a kid, and has never experienced the life of a little girl. Saddened by this, Lee and Alice suggest that the 22-year-old Katherine might want to be treated like their young daughters, so that she can experience childhood when she's not working at the aquarium. Katherine is delighted at the proposal, and is given the pet name of Katie, along with the house rules which make it clear that if she misbehaves, she'll earn a spanking.

So Katie gets lots of new little girl clothes and shoes, books and hair ribbons, cute bedding and toys - including her first ever stuffed animal, a manatee. Lee and Alice become her loving Mommy and Daddy, and discipline her when she's naughty - and it isn't long before Katie finds out an alternative use for a hair brush! She loves her new lifestyle, and adores playing with the other girls, but sometimes spends far too much time playing instead of studying for her exam... and later pays the price on her bottom for telling lies and not studying. Not all her time is spent being 'little'. Katherine enjoys bonding with the other interns on a night out - but there are consequences to be faced when she drives home having drunk too much alcohol, and later wets the bed. This earns her a switching, and then she is put in drop-seat pyjamas, diapered, and suffers the humiliation of a pacifier and baby feeding bowl. But when her time with the Meres comes to an end, Katy is reluctant to leave her new family, but does so after promising to keep in touch. At least now she understands herself, and knows that inside the grown up Katherine there will always be a little Katie.

Publisher's Note: Becoming Little Katie is an ageplay book. The punishments include humiliation, corner time, spankings, diaper play and mouth soaping. Please don't buy this book if such material is likely to cause offence.