In this bi-weekly series reviewing classic science fiction and fantasy books, Alan Brown looks at the front lines and frontiers of the field; books about soldiers and spacers, scientists and engineers, explorers and adventurers. Stories full of what Shakespeare used to refer to as “alarums and excursions”: battles, chases, clashes, and the stuff of excitement. Greg Bear is one of the most respected science fiction writers to emerge in the latter part of the 20 th century, producing books on a great variety of subjects, in a wide range of settings, with all of them being well-constructed and engaging. So, when I saw that he had written a sequel to one of my favorite novels,