Kiel Tarragot is a cop, a member of the Inspector General Branch (IGB) the police force of the Coalition of Planets. He uses his profession as a way to avoid the personal relationships he isn't very good at or comfortable with. After several years in training, he is coupled with a nonhuman partner; a Maldarian named Varlon, and begins his career. Due to the nature of space travel, it is impossible for him to even contemplate a serious relationship that is until he meets Doctor Susan Merniehm, an anthropologist. During their first encounter Susan determines she and Kiel are destine to become life partners. No act of evasion on Kiel's part can thwart Susan's determination. During their next two encounters, Susan and Kiel continue to be drawn together but Kiel maintains his belief that any relationship can only have a negative effect on his career.
A mysterious mining accident has brought Kiel and Susan together for a fourth time. Kiel attempts to bury himself in his work, but a strange turn of events forces him to reconsider his feelings for the beautiful Denerian. While investigating different aspects of the accident and the mysterious alien artifacts, Susan vanishes from the platform of an alien machine. Devastated, Kiel rushes blindly into an adventure to save Susan. Elizabeth Genrete, another scientist assigned to the investigation, offers to help Kiel search for Susan. United Mines (UM), the company that employed the miners killed in the accident, sends their representative to oversee the situation. David Banyon, a sector vice-president of UM and an old enemy of Kiel's is always seeking a way to advance himself and believes there may be an opportunity in the strange alien machine.
Kiel, two fellow investigators and Elizabeth manage to follow Susan to a strange planet, named Midpoint that is controlled by two fantastic androids. The two lovers are quickly reunited but they and the others in the rescue party are unable to return to their own part of the Galaxy. The androids can provide little information for the travelers. They do explain something about Midpoint and identify the device that transported the travelers as the Gateway. Kiel and his party are sent on an amazing adventure to the home planet of the Shaula. This mysterious race is responsible for all that has occurred but are, at first, reluctant to help the unhappy travelers. Through their telepathic power, they learn about the Coalition of Planets and recognize the situation between it and United Mines as a potential disaster. They are determined not to allow the 'great cycle of time' to be thrown out of alignment and agree to help the weary travelers.
Upon their return, David Banyon decides to steal the Gateway technology for his own selfish use. Unable to stop his unscrupulous activity, Kiel, Susan, and the others are forced to postpone their investigation. They take an unscheduled vacation while Kiel's boss, Chief Brodsky, attempts to straighten out the situation. The coalition is finally convinced to stand up to Banyon and United Mines and allows Kiel's group of investigators, Susan and her team of anthropologists, and Elizabeth with her scientific crew to return to the scene of the original accident, where the Gateway is located.
Banyon manages to convince the company that only an armed conflict will allow him to gain control of the Gateway for the company. During the battle, many are lost until the strange Shaula take control of the situation. The Shaula manage to end the conflict and set into motion events that lead to the end of United Mines. Susan, at last, convinces Kiel to marry and they begin their new life, never fully realizing the impact the Shaula have had on their lives or how this mysterious race will affect their future.