Soon after taking the vows, she discovers she has the ability to fly. The coronets (or headdress) worn by the nuns of her order have sides that resemble wings, and San Juan is located in an area affected by trade winds. Sister Bertrille, who weighs in at only ninety pounds, is able to soar above the ground when caught by strong gales. Through the manipulation of her coronet, she acquires some control over flight, but landings remain difficult.
The series depicts Sister Bertrille's efforts to use her gift of flight to help benefit the people of her poverty-stricken parish.
