Meggymoo, here goes.
English couple had tried IVF etc but woman couldn't have baby. She tried to kill herself so wasn't allowed to adopt in this country and went to an agency in Canada. They adopted 2 girls whose mother had been brutally murdered while they hid in a closet.
The little one (Grace)was ever so cute but the older one (Heather) did creepy things like sleepwalking and trying to stab her adopted half-brother with scissors. The woman (Tess I think) started digging and discovered that the pair had been adopted loads of times before and jumped to the conclusion that Heather had killed her real mother and was trying to kill her too. She decided to take her back to Canada to try and find out the truth of what happened. When they got to the house where the grisly murder took place Heather remembered what happened. There had been a noise downstairs and her mother had told her to get in the closet with her baby sister and call the police. Through a crack in the door she saw her mother being murdered and saw a silhouette of the murderer.
Later on they went to see the man who ran the adoption agency to ask to see the girls' files to see if there were any clues. While he was silhouetted in the doorway Heather realised that he was the murderer and the two tried to escape, calling the local police on their mobile. Adoption man (Alvin) followed them with a shotgun and stopped them getting in the car. It all came out that he was killing 'bad' parents so that their kids could have a better life (his excuse but he was also making loads of money)and that the policeman who had since arrived was covering up for him. Alvin shot the policeman and was about to shoot Heather but Tess grabbed the dead policeman's gun and shot him instead. All lived happily ever after.
Ok, think that's it. Not bad considering I was also turning out the cupboard under the stairs looking for an embroidery hoop which happened to be right at the back! I could see the tv through a crack in the door.