This is the third installment of Baxter's excellent 'Time's Tapestry' series. It is a little less compelling than the second (Conqueror) but still an absorbing and intriguing novel. The premise of the series - which began in ancient Rome and has now reached the time of Columbus - is that meddlers from the future are sending back messages - warnings and prophecies - into the past in order to alter history. Although the SF premise creates an atmosphere similar to that of 'counterfactuals' - such as Kim Stanley Robinson's The Years of Rice and Salt - the main political events in 'Time's Tapestry' seem to be historically accurate, although the possibility of a swerve into alternate history is always present. Although this installment seemed just a bit thin in places it was good to see Baxter ratcheting up the overarching plot and giving us a few more hints about the mechanisms behind the central conceit of implied time travel. Readers should certainly start with the first of the series, Emperor, and if you like 'Time's Tapestry' you will probably also enjoy Baxter's earlier Coalescent.