Alex Fitch looks at the science-fiction sub genre of Alt. History, talking to three novelists about their works in the sub-genre: Charles Stross discusses his parallel worlds series Merchant Princes plus his collaboration with Cory Doctorow on Rapture of the nerds; Max Brooks talks about his popular zombie epic World War Z and spin-off titles; and Ken MacLeod discusses his novella The Human Front and novel Intrusion. (More info: www.antipope.org/charlie / www.maxbrooks.com / www.kenmacleod.blogspot.co.uk)