The final play of the Pistarckle Theater 2018-19 Season is the engrossing, provocative drama “Doubt,” written by John Patrick Shanley and directed by Frank Barolucci, Pistarckle’s resident director. In 1964 the winds of change are sweeping through Sister Aloysius’ St. Nicholas School. Father Flynn, a charismatic priest, is advocating reform of the school’s strict customs, and the first black student has just been accepted. When a fellow nun tells Sister Aloysius that Father Flynn may be paying too much personal attention to the student, Sister Aloysius begins a personal crusade against the priest — despite her lack of evidence.