What if the Silurians had killed the Third Doctor in the 1970s and taken over the earth, leaving the Brigadier and Liz Shaw as leaders of a hunted and dwindling human resistance? Jim Mortimore brings the Seventh Doctor, Ace and Benny to a parallel universe to find out. It was particularly interesting to read it soon after listening to a slightly different alternate timeline for Liz (The Sentinels of The New Dawn) and also the Ace-in-devastated-England stories, Project: Destiny and A Death in the Family, which Big Finish did last year. Mortimore writes engagingly and I kept turning the pages, but I was not totally convinced by some of the details - the use of the Tardis to sort things out at the end, or the Jo Grant time line, or the plausibility of two decades of human resistance (including a functioning nuclear submarine). Still, a pleasing read, with the ending setting up (I suppose) a story arc for the next few novels.