According to playwright David Mamet, “Age and treachery will always beat youth and exuberance.” And, if 93-year-old Thelma Post (June Squibb) has anything to say about it in this fact-based action-comedy-drama, you can take that notion to the bank. In this story of a spry but sometimes-gullible widowed retiree living on her own, we watch – often in jaw-dropping awe – a feisty, independently minded senior determined to get her money back when she’s scammed out of her funds in a phone-based phishing scheme. Thelma says nothing about her plan to her family (Fred Hechinger, Parker Posey, Clark Greg...