Constanze, her English maid Blonde and her fiancé Pedrillo were taken prisoner by pirates, who sold them as slaves in Turkey to Bassa Selim. Pedrillo's managed to get word to Constanze’s betrothed, Belmonte, who's on his way to try and rescue her. Act 1 At his first attempt to enter Bassa Selim’s palace Belmonte's threatened and chased away by Osmin. Pedrillo has to put up with Osmin’s tirades about everything »foreign« on a daily basis. When he approaches the palace again Belmonte meets his servant, who tries to point out what deadly risks they run with the planned abduction. Belmonte throws all caution in the wind. He's too excited about seeing Constanze again. Selim and Constanze are alone. The Bassa feels deeply drawn to her but doesn't want to force her to be his wife. She tries to explain why she must refuse him: thoughts of her beloved at home weigh heavily on her heart. Full of understanding, Selim postpones further argument to the following day. Pedrillo introduces Belmonte to the Bassa as an architect and Belmonte gains entry to the palace. Osmin tries to stand in the way but is mocked by Belmonte and Pedrillo. Act 2 Osmin loves Blonde. She needs all her strength to resist his advances. They argue when he tries to demand his right, as her master, to make her love him. She furiously fends him off. Constanze's anxious about the forthcoming meeting with the Bassa. When Bassa becomes more impatient and threatens force if she refuses him again, she declares that she'd rather die than be untrue to her love. Pedrillo tells Blonde about Belmonte’s arrival. Constanze and she will be abducted, this very night. Before this happens it's arranged that Constanze and Belmonte meet in the garden. Meanwhile christian Pedrillo, manages to tempt muslim Osmin, to drink. A sleeping draught's mixed in the wine, which should render him harmless for a few hours. Belmonte and Constanze see each other again. Tears of happiness and feelings of anxiety colour their meeting. A dark shadow looms when both men cast doubt over the faithfulness of their brides, but the girls forgive them. Belmonte and Constanze, Pedrillo and Blonde renounce jealousy and let love live. Act 3 All are waiting nervously for midnight. The abduction backfires. Osmin, awake earlier than envisaged, has arrested both couples and informs the Bassa about the happenings during the night. Selim realizes that Belmonte's the son of his one time deadly enemy and threatens terrible revenge. Fear of death draws Constanze and Belmonte together. They all face execution. But the Bassa has second thoughts. He grants them their freedom and takes his leave from Constanze.