When Danni arrives for a new babysitting job which was arranged by phone the day before, she is confused that the "baby" she's supposed to look after seems to be quite a lot older than she was expecting. Aleisha is looking very cute, lying on the couch and claiming to be only 2 years old. When Aleisha gives Danni a note written by her Mom, she is shocked to read that part of the job includes putting her in diapers!
Suspecting maybe some kind of practical joke or possibly that Aleisha herself arranged the whole thing, Danni calls the number on the note, only to be reassured by Aleisha's Mom that she does indeed need a babysitter and since she isn't yet potty trained also needs to be diapered!
It seems like Danni's only option is to proceed as normal like she would for any little girl, and decides to get Aleisha to do some drawings. Aleisha is not totally cooperative though, so Danni thinks Aleisha might enjoy having her hair put in pigtails while she draws and sucks her thumb. All seems to be going ok, but then Aleisha announces that she needs to be diapered because she wants to poop!
Danni is dumbfounded, and tries to convince Aleisha to use the bathroom, but to no avail. Aleisha is determined to be diapered. Danni finally complies, but still tries to convince Aleisha to be a big girl and use the toilet. She even cuddles her on her lap and talks to her, trying to understand what's going on. And then when Aleisha admits she intends to play in her diaper, it suddenly hits her and it all makes sense!
"I think you're a smart girl, and you don't need diapers. You're pretending, because I understand something - you like to play with diapers! Is that making you horny - is your little pussy horny?" Aleisha admits that it does!
This realization is a bit too much for Danni, and while still trying to get Aleisha to use the toilet, she also threatens that if she goes ahead and messes herself, she will call her Mom and tell her everything - that she likes being taken care of, to be diapered and cleaned up, and even that it makes her horny! But Aleisha is not listening, and proceeds to defiantly fill her diaper with a messy load of poop! Danni is aghast and can't believe what's happening, and leaves the room to call Aleisha's Mom.
Once alone, Aleisha proves that she is indeed very excited and turned on by what's she's done, and starts to play with herself and be a really dirty girl. She rubs the messy diaper against her pussy, and smears the poop on herself, at one point even wandering the room with the open and poop filled diaper hanging between her legs.
Totally filthy and covered in poop, she continues to masturbate herself until she reaches a satisfying orgasm. Danni was obviously right - Aleisha is really just a dirty little girl who pretends not to be toilet trained because it turns her on. Maybe after Danni tells her Mom, it won't be so easy to get away with it in future.