Yes indeed. Women are absolutely crucial to this. Not only with Catherine, but with the mother of the little girl who is killed with the bomb at the start.

" You see it's because I know that you have children too... and that this is real for you, that these men caused this tragedy. And I know that you will put a stop to them. I know you'll do that now."

Such a powerful moment. Every time I watch, it makes me want to join Elliot Ness immediately and put an end to Capone (despite the absolute lunacy of prohibition as a law). The timing of the scene is vital too, as it comes just after a major screw-up, thanks to someone in the police tipping off the mobsters about the liquor raid. Ness was determined before, but now the real damage caused by Capone is right in his face. Now it's essentially a vendetta.