Hello to Jason Isaacs.
This is a real headscratcher. If you come to 'Mass' unprepared you have both a treat and a problem on your hands.
I would recommend going into it as fresh as possible and let the chips fall where they may. Kranz' directorial debut, impressive as it is, and sometimes painfully, purposely slow, gives up its nuggets appropriately and despite not knowing the reason for these four individuals gathering in a church meeting room that day, there is no sense that boredom will set in before the reason is revealed.
Far from it.
Acting -wise, we have four major players all heavy-hitting and fully and completely involved in their jobs. You rarely witness such quality confined to one room for such a prolonged period.
As a parent, you will almost certainly be brought to tears by the very reality that is created by any or all of the cast featured most prominently, such are their breathtakingly powerful performances.
This is acting folks. Deal with it.