Little Darlings by Melanie Golding

A creepy debut that mixes old fairy tale thinking with psychological trauma after childbirth that no new mother should be allowed to read.
Postpartum depression and sleep deprivation can cause rational women to do some really irrational things but when Lauren is found locked in a bathroom with her children screaming that a strange woman tried to steal her babies, not once but twice, the police and Lauren's husband really don't know what to make of things. With little evidence other than "mother's intuition", a policewoman and journalist try to prove Lauren's claims. You too will fall into the sleep deprivation category because once you begin this twisty tale you will not stop until its chilling conclusion. This is the stuff that nightmares are made of.