Thread: Please help on me name this movie!?

Hi, my friends birthday tomorrow and she tells me she loves babysitting movies. So i was planning on getting her this one movie but i dont remember the name.
The movie is where this girl caught her boyfriend cheating with her bestfriend, then she goes off to babysit 2 kids for this couple. Then she gets a phone call and someone tells her to check on the kids and then they are gone and that caller tries to kill her and that guy ends up getting arrested instead.

Anyone know the name of this movie?

Oh yeah that is When a Stranger Calls.