Terrible events unravelled in the village of Hulster in Yorkshire in the autumn of 1678. But all debate was suppressed by the authorities. They dreaded the consequences for the security of England if certain aspects became known. Indeed, they feared for the very future of Christian Civilisation. Fifty years later, Erasmus Penn is summoned by the Lord Chancellor. He reveals how Isaac, the most famous natural philosopher of the age, helped to solve the mystery of the 'Hulster Secret'.