The first thing we see is the calm looking scene of a field, this gives the impression that the atmosphere is idyllic and tranquil, which couldn't be more wrong. A sinister tone is created when a young girl playing by herself is shown in the field alongside the eerie piano music that starts to play. The use of mis-en-scene and non-digetic sound suddenly creates tension showing the viewer that the peacefulness is about to be shattered by danger. This technique of tranquillity versus immanent danger is a commonly used introduction to Thriller films.
Another common convention of Thriller openings that the film uses is made use of when the scene of the field cuts to one of the man and woman. This is used in many Thriller films - when there is a suspense building opening which then cuts to the main storyline. This tension is sustained by flicking between these two scenes, panic and tension is created in both, until they eventually meet. In the field scene the child starts to run and another boy enters and then falls off his bike, and in the other scene the man is finding clues (picture in a church of somebody in a red jacket like the girl). Moreover we get the impression that the child is going to be the source of drama and suspense.