When Theresa (Fiona Gubelmann - 911 Nightmare) ended up in rehab, due to alcohol problems, her daughter, Sadie (Emma Hentschel), went to live with Elana Connell (Deborah Grover - The Perfect Girlfriend), her paternal grandmother who believed in old school discipline. But after remaining sober for 3 years and having married Aaron Myers (James Gallanders - Hidden Crimes), who already had a son from a previous marriage, Theresa shows up at the Connell home to take Sadie home to live with her. But it seems that the time spent with her grandmother has changed Sadie and not only does she have some screwed up views on doing things right but she will do anything to make sure she doesn't return to her grandmother's either.
Whilst the classic tale of "Goldilocks" featured three bears I reckon "Mommy's Little Girl", which is also known as "Mommy's Little Murderer", could have been called "Goldilocks and her psycho alter ego". To put this simply we have little Sadie with her little girl hair and perfect smile who is nice to grown ups, telling them what they want to hear, like butter wouldn't melt in her mouth. But what we see is that time with her grandparents has turned her into a little monster who turns nasty towards anyone who crosses her, and that includes killing grown ups who might spoil her new life. We do get some motive for her twisted personality as we discover that granny Connell is just as twisted and evil whilst there were things in Sadie's past involving her grandfather that also help explain why she is such a troubled young girl with psychotic tendencies.
The thing is there isn't much else to "Mommy's Little Girl" and as such what we get often feels like a series of scenes as we watch Sadie acting like a spoilt brat and then doing some thing nasty and often psychotic when ever some one upsets her. That is it till eventually Sadie's almost serial killer side becomes clear for others to see. In fairness Emma Hentschel certainly does an entertaining job of giving us cute little nice girl mixed with seriously unhinged but there needed to be more than just this series of junior psycho scenes to stop "Mommy's Little Girl" from feeling one dimensional.
What this all boils down to is that whilst there is some sort of strange entertainment from watching Sadie act psycho there is not much else to "Mommy's Little Girl". As such after a while this made for TV movie becomes a little monotonous and just a series of acts of evil from an unhinged young mind.