When two gang members choose Mary Harrington as their target, the quiet widow has a secret to share of her own

Most people in the town of Rivershore, Michigan view Mary Harrington as a quiet widow whose only oddity is that she spends a lot of time at the gym. Her son thinks it's time for her to move into a retirement home. Two gang members think she'll be an easy target. No one in Rivershore knows what Mary did in her younger years--really did--but the two gang members discover they've underestimated their victim . . . and Mary fears reverting to old habits may have jeopardized her future.