We instead agreed against this idea and wanted to create a opening sequence where nothing obvious therefore leading to the the audience asking questions and building anxiety to find out what happens later on during the film.
The idea we came up with finally was: a man staggers out of a lift, then its a flash back of earlier events. 3 people get a phone call, they all are called to a building, at arrival they are all surprised to see each other there, they then follow signs on the wall that lead them to a room where a man awaits them, at this point the opening ends.
The effect of the idea is that the audiences raises several questions. This builds both suspense and anxiety. We also haven't shown them enough for them to lose interest as they don't know the out come of the situation. We created are opening with a the idea that we want the audience to maintain an interest in the film beyond the opening.