George R. R. Martin, the author behind the wildly popular Game of Thrones series, is 75 percent finished with The Winds of Winter, the next installment series, Martin said on The Late Show with Stephen ColbertTuesday night. “I think it is going to be a very big book,” Martin said. Despite rabid anticipation from fans, Martin hasn’t published a fresh installment to his saga since the debut of the Game of ThronesHBO series in 2011.