The Black Book of Bran is an ancient book of prophecy written by an Irish sixth century monk perhaps similar to Nostradamus, that foretells disasters or murders.

Bernard Knight's character, Sir John De Wolfe of Exeter in the 12th Century is out for walk with his dog when he surprises some burglars in a library building in an adjacent street. There was a lot of commotion and a servant was killed but underneath his body was The Black Book of Bran. Sir John as Coroner was the only law officer and investigated the murder which seemed to be tied up with a lot of local treasure hunts.

In the next Act, Nick Zuliani the merchant of Venice character of Ian Morson, in 1262, is caught in severe weather in the Russian Crimea. He is looking for business and he is obliged to take shelter from a snowstorm in a stove house which is filled with Tartars. Nick has the opportunity of cheating these people for any money they possess and he does so with relish until one is murdered and in the confusion he is charged with the murder.

In the following Act, Michael Jecks' Keeper Sir Baldwin de Furnshill and Bailiff Simon Puttock are in London in the year 1323 and are staying at the Priory of Westminter Abbey when there is a ghastly murder: a murder of a monk in an incredibly cruel and savage manner. It occurs in the crypt and there is blood everywhere.

In the next Act, it is 1350 and in Cambridge where Susanna Gregory's characters Brother Matthew Bartholomew and Brother Michael become embroiled in an effort to stop mayhem between two sister colleges over murders caused in part by The Black Book of Bran.

The penultimate Act describes how Philip Gooden's Nick Revill, in August 1605, receives a mysterious letter from an unexpected relative.

The final chapter written by C J Sansom shows how his character Shiva handles the events leading to the day of judgement.