Window in the Sky — Paul J. Joseph

With a lasting peace established between Earth and Baltan mediated by the growing alliance with the mysterious Szzzyyyxx, a new chapter in human history begins. But in the midst of this, the Szzzyyyxx Mother requests Sally's help with a mystery. Two Szzzyyyxx vessels have disappeared in the far reaches of their space. Sally and Ian plan a controversial rescue mission with the first of a new line of experimental ships. They arrive in the region to discover a fold that doesn't appear to go anywhere. On closer inspection, however, they find evidence of a black hole and a strange world that defies understanding. Through the use of a machine established in eternity, The Szzzyyyxx have teleported to Earth in the 1960s. There, captured by the KGB, they unwittingly help a rogue agent rise to power and dominate the Earth. But the power he uses to do this opens a door to something far worse. With their own past erased, Sally and her crew must rebuild history and defeat an ancient and universal evil.