race against time

climax critical point crux culmination juncture twist

axis change climacteric contingency crisis critical mass critical moment critical period crossing crossroads crucial moment crucial occurrence crucial period crunch cusp decisive moment defining moment development emergency exigency high noon hinge kairotic moment moment of truth nexus pass peak peripeteia pinch pivot pivotal moment point of no return rising action shift strait transition turn of the tide when push comes to shove zero hour