the weakest parts of the plot were the arrangements for the subsequent rebellion which would have swept the country and installed a catholic monarch. due to the requirements for money and arms, sir francis tresham was eventually admitted to the plot, and it was probably he who betrayed the plot in writing to his brother-in-law lord monteagle. an anonymous letter revealed some of the details of the plot; it read: "i advise you to devise some excuse not to attend this parliament, for they shall receive a terrible blow, and yet shall not see who hurts them".