The deadliest sin

In the spring of 1348, tales begin arriving in England of poisonous clouds fast approaching, which have overwhelmed whole cities and even countries, with scarcely a human being left. While some pray more earnestly and live yet more devoutly, others vow to enjoy themselves and blot out their remaining days on earth by drinking and gambling. And then there are those who hope that God's wrath might be averted by going on a pilgrimage. But if God was permitting his people to be punished by this plague, then it surely could only be because they had committed terrible sins? So when a group of pilgrims are forced to seek shelter at an inn, their host suggests that the guests should tell their tales. He dares them to tell their stories of sin, so that it might emerge which one is the best. That is, the worst.