Need A Movie Name Please

Me & my partner are very keen to watch this movie again but only know the plot ,so here is the plot,

A couple go away on holiday who are having an affair , She goes out in a vehicle to get some things she goes to get fuel & she notices a SUV  parked a little bit in  front of her & notices that a small hand writing on the rear window on the condensation HELP.

She goes to intervene but the vehicle drives off so she decides to follow it , she ends up miles away from anywhere in a rural location ,

She climbs over the locked gate  And walks to the house & starts looking through the windows & notices this odd couple have some children kidnapped , She goes to try & get away unnoticed but fails & gets kidnapped herself .

She is pregnant so they keep her alive until she has the baby .

In the meantime her partner is frantic & looking for her ,

Not sure how she gets away but she does but only after having the baby ,

It is an excellent Thriller & would love to see it again i watched it around 2017 on the cinema app on a fire stick.

I have searched & searched the cinema app but cannot find it .

Many thanks for your help