suspense builder clips

my group recently looked at all the footage we have and discovered from the timing of each of our clips that we are 30 seconds short of the 2 minutes we need for our film opening. we plan to fill this gap with clips that will build up the suspense to the moment when our main character played by louis stabs ben and kills him. some of the clips my group thinks will be useful are louis preparing to stab ben i.e. grabbing the knife, getting madder after drinking alcohol. miss also suggested that we make this a montage with music that gets louder or more rhythmic as louis gets more and more mad. i thought the sound effect of a heart beat might work for this. especially if the heartbeat gets faster the more angry louis gets.