The Outrim Void is a dangerous place, rife with the remnants of ancient civilisations, pirate havens and ravenous aliens waiting to surge across borders into unclaimed territory. Its only hope for survival is the narrow stream of stars known as the Sindalian Main. If the secure flow of trade can be restored there, the region might one day rise above its blighted circumstances. The Travellers are sent deep into the Void when they are assigned to the remote Imperial Navy base at Dpres. There they must take command of a joint-force task group and proceed along the Sindalian Main to Tktk.