Darnley was both incompetent and unmannerly, violent and weak. The affection which he had inspired in Mary Stuart soon disappeared and gave place to contempt. She has been accused of worse still; the niece of the Guises, brought up by Catherine of Medicis, amidst all the disorder of morals which reigned at the court of France, had a bad reputation among the austere Presbyterians; they attributed the most unworthy motives to the elegant tastes for frivolous pastimes which led the queen to surround herself with young men, with foreigners and artists. No one was more suspected among the favourites of Mary than an Italian, David Rizzio, who had won her good graces by his musical talents, and to whom she had gradually confided important trusts. Rizzio had especially aroused the jealousy of Darnley; the Italian had, it was said, taken the liberty of reproaching the young king with his behaviour towards Mary; he also encouraged the queen in her refusal to confer upon Darnley the crown as her consort instead of the vain title which he bore. A plot was hatched against the life of Rizzio. At the head of the conspirators was Lord Ruthven, who had been a short time before in a dying condition, and who arose from his sick-bed to take part in a deed of blood with Lord Morton, chancellor of the kingdom. Their aim was to recall the Earl of Murray and the exiled lords, by revoking the acts passed against them by Parliament.
On the 9th of March, 1566, Mary was supping in her apartment with her ladies, and Rizzio was in the room, when the young king came to the palace, followed by Ruthven. The queen rose in alarm, for the other conspirators had just entered. Ruthven ordered Rizzio to leave the chamber, but Mary placed herself before her favourite, who clung to her dress. Darnley seized the hands of his wife; the table was overthrown; the unhappy Italian cried, "Mercy! justice! justice!" George Douglas drew the dagger of Darnley, and struck the secretary. Andrew Ket, one of the conspirators, presented his pistol close to the body of the queen, who implored them to spare Rizzio. He was dragged out, and was pierced by numerous dagger-thrusts in the antechamber, while Morton guarded the doors of the palace with a troop of armed men. When Mary heard that Rizzio was dead, she stood erect. "I will now dry up my tears," she said, "and I will think of revenge." Darnley endeavoured to console the queen; she suffered him to believe that she accepted his excuses, and when his brother, Lord Murray, presented himself on the morrow at Holyrood, with the banished noblemen, she received him without anger, and contrived to detach him from those who had exerted themselves on his behalf, perhaps without his knowledge. Morton and Ruthven, abandoned by Darnley and Murray, immediately took to flight, while the Earl of Bothwell and Lord Huntley were bringing to the queen an army of eighteen thousand men, that they had immediately levied. Mary was once more mistress of the situation. Two obscure accomplices in the murder of Rizzio alone bore the penalty of the crime, and on the 9th of June, 1566, the queen gave birth to a son, who was to become James VI. of Scotland, and James I. of England. Elizabeth had promised to act as godmother to the child of the Queen of Scotland. When the prince was born, Melville departed in all haste, to bear the news to London.