Day of Octagon (Paperback) (ISBN-13: 9781734330090)

Set after the events of The Risen Period Trilogy, The Core heroes have went there separate ways, on about their individual business.

Yet, they will be united once more when a threat arises from another realm and even sooner when the rise of an artificial intelligent force known as Octagon sets out to transform the world into a land of only machine and digital.