An abortive international Catholic conspiracy, intended to put Mary, Queen of Scots on the English throne in place of Elizabeth I. It took its name from Roberto di Ridolfi (1531–1612), a well-connected Florentine banker who had settled in England. The English Catholics were to rise under Thomas Howard, 4th Duke of Norfolk. Then, with papal finance and Spanish military aid, Elizabeth was to be deposed in favour of Mary, who would marry Howard. Elizabeth's intelligence service uncovered the plot and its leading figures were arrested.