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Only Dobelle and the gas-giant called Gargantua remained, their still-changing orbital elements allowing an accurate reconstruction of past events.
    Summertide, Dobelle's time of closest approach to Mandel, was just a couple of weeks away. It would be a time, if Darya Lang's analysis was correct, of great significance in the spiral arm. And also in her own life. Her theories would at last be proved true.
    Or false.
    She went to the port and watched as the ship approached Dobelle. Opal and Quake whirled dizzily around each other in a mad dance, spinning three full turns in a standard day. She could actually see their motion. However, speed was all relative. The ship's rendezvous with the landing field on Opal's Starside sounded difficult, but it was a trivial problem for the navigation computers that would make the rendezvous.
    The problems would come not from there, but from the humans who wanted to greet her. The tone of the message permitting her entry to Opal sounded ominous. "Provide the full identification of your sponsor. State in full the proposed length of stay. Give details of expected findings. Explain why the time of your requested visit is critical. Say just why you wish to visit Quake. Provide credit information or nonrefundable advance payment. Signed, Maxwell Perry, Commander."
    Were the immigration officials on Opal so hostile to every offworld visitor? Or was her paranoia not paranoia at all, but a well-merited uneasiness?
    She was still standing by the port as the ship began its final approach. They were coming in from the direction of Mandel, and she had a fine sunlit view of the doublet. She knew that Opal was only slightly larger than Quake—5,600 kilometers mean radius, compared with Quake's 5,100—but the human eye insisted otherwise. The cloud-covered iridescent ball of Opal, slightly egg-shaped and with its long axis pointing always to its sister world, loomed large. The darker, smaller ovoid of Quake brooded next to it, a smooth-polished heliotrope against the brighter gemstone of its partner. Opal was featureless, but the surface of Quake was full of texture, stippled with patches of deep purple and darkest green. She tried to make out the thread of the Umbilical, but from that distance it was invisible.
    Entry to the Dobelle system offered no options. There was only one spaceport, set close to the middle of Opal's Starside hemisphere. There was no spaceport of any kind on Quake. According to her reference texts, safe access to Quake came only via Opal.
    Safe access to Quake?   
    A nice idea, but Darya recalled what she had read of Quake and of Summertide. Maybe the reference texts needed to find different words . . . at least at this time of the year.
    The reference files of the Fourth Alliance had even fewer good things to say than Legate Pereira about the worlds controlled by the Phemus Circle. "Remote . . . impoverished . . . backward . . . thinly populated . . . barbaric."
    The stars of the Circle lay in a region overlapped by all three major clades of the spiral arm. But in their outward expansions the Fourth Alliance, the Zardalu Communion, and the Cecropia Federation had shown negligible interest in the Phemus Circle. There was nothing there worth buying, bargaining for, or stealing—hardly enough to justify a visit.
    Unless one was looking for trouble. Trouble was supposed to be easy to find on any world controlled by the Circle.
    Darya Lang stepped out of the ship onto the spongy ground of Opal's Starside spaceport and looked around her with misgiving. The buildings were low and ground-hugging, built of what looked like plaited reeds and dried mud. No one was waiting to greet the ship. Opal was described as metal-poor, wood-poor, and people-poor. All it had was water, and lots of it.
    As her shoe sank an inch or two into the soft surface she felt even more uneasy. She had never visited a waterworld, and she knew that instead of hard rock and solid ground beneath her feet, there was