Venus Prime

After her sudden escape from a mental institution, an amnesiac who calls herself Sparta seeks out the origins of her unusual abilities. To this end, she adopts the identity of Ellen Troy and becomes an inspector for the Space Guild.

On her first assignment as an Inspector, Sparta is sent to Port Hesperus, the space station orbiting Venus, to investigate the sabotage of the Star Queen, an old freighter. While there, she encounters Blake Redfield, a young antique books expert who may hold the key to her missing memories.

After taking a break on Port Hesperus, Sparta is sent to Venus proper to rescue a team of scientists who have become trapped there. Her successful rescue leads to the recovery of an artifact that may prove the existence of extraterrestrial life. Afterwards, she is sent to Luna to investigate the attempted sabotage of the local magnetic slingshot.

Meanwhile, seeking to help Sparta learn more about her past, Blake goes undercover in Paris, infiltrating the Athanasian Society, a supposed charity that provides shelter and other services to homeless youths. After getting in, Blake confirms that the society is a front for the Free Spirit, the cult that was responsible for making Sparta more than human.

Sparta and Blake are deployed to Labyrinth City, the glass colony on Mars, to investigate two murders that may be connected to the theft of the "Martian plaque", an artifact that proves that Mars was once inhabited.

The pair split up, with Sparta tailing one suspect, Dr. Khalid Sayeed, and Blake tailing the other, trucker Lydia Zeromsky. Things do not go as planned, however; Blake's efforts to investigate Zeromsky soon get him embroiled in the political intrigue of the local unions, while a plane ride with Dr. Sayeed ends with an explosion that nearly kills her.

A third murder leads them both to the real culprit, an assassin hired by the Free Spirit, and from there, Sparta manages to deduce the location of the missing plaque, leading to a race against the Free Spirit's operatives.

Recovering from her mission on Mars, Sparta finds herself the guest of the Space Board. But relaxation is short-lived as she sets out on an interplanetary investigation — of the Space Board itself! Members of the Free Spirit, a religious cult intending to gain control of all the worlds of our galaxy, have infiltrated the Space Board. As the date of the manned mission into the clouds of Jupiter approaches, Sparta's suspicions grow. She is certain the mission has fallen into the hands of the cult, and she is determined to stop it.

Much excitement has arisen throughout the galaxy over the exploration mission to Jupiter's moon, Amalthea. Led by the renowned Professor J.Q.R. Forster, the dangerous expedition will lead its members to the surface of this strange moon – and beyond. It is Sparta's mission to monitor the trip on the part of the Board of Space Control. Her task becomes more threatening when Sir Randolph Mays, Forster's rival and nemesis, "accidentally" crash-lands on Amalthea's surface. Far from innocent, Mays has a plan for laying claim to Forster's discoveries, and only Sparta is able to prevent sabotage. But what is Mays really after? And how will they all react to the discovery of an alien life-form...?

World-renowned professor J.Q.R. Forster's expedition to Jupiter's moon has not proven uneventful. In a furious blaze of ice-geysers, the moon's surface rips off to reveal an ancient alien world-ship. But when the world-ship suddenly hurtles through space toward a black hole, Sparta must find out why, and soon, from a mysterious alien from an unknowable culture, little knowing that what is about to unfold will determine the future of Earth. As the alien ship charts its ancient course, the scheming Sir Randolph Mays and Sparta unwittingly head for their final battle through the eons in the midst of an ancient galactic civil war.

• Sparta – A young woman with a mysterious past and various superhuman abilities, including eidetic memory and enhanced senses. Formerly enrolled in the mysterious SPARTA program under her birth name, Linda Nagy, she now works for the Space Board under the name Ellen Troy, hoping to gain enough security clearance to eventually learn why a large chunk of her memory has been erased.
• Blake Redfield – A brilliant young expert dealer in old and rare books, and one of Sparta's fellows from the program. Also Sparta's main ally and romantic interest.
• Dr. Khalid Sayeed – A Council of Worlds planetologist based on Mars, and another graduate of the SPARTA program. Initially a suspect in the murders on Mars, he ends up aiding Sparta's investigation. A devout Shiite Muslim, he enjoys debating religion, and carries around a modified astrolabe so that he can always pray in the direction of Mecca, even when he's in space.
• The Commander – Sparta's boss at the Space Board. Described as having an unusually dark face and hands, the result of spending too much time in deep space with inadequate protection against UV radiation.
• Dr. J. Q. R. Forster – A scientist who discovered the Culture X artifact on the surface of Venus and nearly figured out how to translate it.
• The Free Spirit – A eugenicist cult, and the series' main antagonists. They believe that Culture X is coming to accelerate the evolution of the human race, and intend for that evolution to be enjoyed solely by themselves. To this end, they seek to prepare a small society of gifted individuals, while simultaneously stealing or destroying all of Culture X's artifacts, and eliminating any outsider who might figure out how to comprehend their significance.
  • William Laird – A prophet of the Free Spirit, charged with running its eugenics programs. To this end, he took over the SPARTA program and was directly responsible for Linda Nagy's augmentations. Under the pseudonym Lecqueau, the founder and CEO of the publishing company Editions Lecqueau, he is also the director of the Athanasian Society, a supposed charity in Paris that funnels homeless youths and immigrants into the Free Spirit to serve as footsoldiers and operatives. After Blake infiltrates, is uncovered, interrogated, imprisoned by, and escapes the Athanasian Society, Laird must assume a new identity, that of TV personality Sir Randolph Mays, who later becomes involved with the Almathea expedition and intends to sabotage it.
  • John Noble – A prophet of the Free Spirit. The profits from his company, Noble Water Works, helps fund the cult's operations, and his position in the charitable organization called the Tappers enables him to find new recruits. Killed by Sparta in her attack on Rupert Kingman's manor.
  • Rupert Kingman – A prophet of the Free Spirit, and one of its financial backers. After he is sent on a failed mission to retrieve the stolen Martian plaque, Laird has him killed as part of an effort to take over the Free Spirit's leadership.
  • The Orange Man – An assassin in the Free Spirit's employ.
  • Katrina Balakian – One of Laird's deputies. Under the pseudonym Catherine, she helps indoctrinate new initiates into the Athanasian Society.
  • Dr. Albers Merck – A Free Spirit mole in Dr. Forster's team. He dies after trying to kill Forster in a suicide bombing.
  • Karen Antreen – A Free Spirit mole, serving as the head of security at Port Hesperus. Debilitated at the end of Book 1, following a failed attempt to kill Sparta.
  • Dr. Holly Singh – A Free Spirit prophet, and the developer of the biotechnology used to augment Linda Nagy, she is a ruthless woman who destroys a lot of people (including a young girl) in order to accomplish this, and who also tries to get a biotech augmented chimpanzee to kill Sparta when she visits Singh at her home in India. She is later killed by Sparta during an attack on Kingman's manor.

• Inspector Viktor Proboda – A Space Board inspector assigned to Port Hesperus, and Ellen Troy's partner in the investigation of the Space Queen sabotage.
• Sondra Sylvester – An executive at the Port Hesperus branch of Isthar Mining Company. Constantly at war with former boyfriend Vincent Darlington, her obsession with stealing a highly valuable book from Darlington initially makes her a suspect in the sabotage of the Space Queen.
• Nancybeth Mokoroa – Sondra Sylvester's companion and lover. Formerly companion to Vincent Darlington. Described as highly attractive, but fickle and temperamental.
• Vincent Darlington – Former lover of both Sondra Sylvester and Nancybeth Mokoroa, and the owner of the museum of Port Hesperus. Sought revenge against the two women by outbidding Sylvester for a highly valuable book. Killed by Sylvester at the end of Book 1.
• Inspector L. Sharansky – A Space Board inspector, assigned to Mars Station. Has been trying to defuse the tensions between the local Pipeline Workers Guild and the Space Transportation Workers union. She is also a cousin of Inspector Proboda.
• Yevgeny Rostov – A high-level operative of the Interplanetary Socialist Workers Party, and the business manager for the Pipeline Workers Guild on Mars. A staunch socialist, he and his group are embroiled in a bitter dispute with the Space Transportation Workers union, which is trying to absorb them, or failing that, to steal away the PWG's contracts with Noble Water Works.
• Lydia Zeromsky – A driver with the PWG, and the lover of murder victim Dare Chin.
• Peter Grant – The co-captain of the Space Queen, an old starship. When the ship is sabotaged during an expedition, leading to its oxygen supply becoming too low to last the entire trip, the normally-disciplined Grant becomes convinced that the only way to survive is to kill his co-captain, McNeill, and thus slow down the rate of oxygen depletion. His attempt fails, however, and instead McNeill convinces him to kill himself.
• Angus McNeill – The co-captain of the Space Queen. Unlike his colleague, Grant, McNeill is a hedonist, and when the ship begins to lose oxygen, he resolves to make the best of a bad situation, which causes Grant to eventually try and kill him. When the attempt fails, McNeill convinces Grant to play a game of cards to determine which of them will commit suicide so that the other might live long enough to reach their destination, and he ends up winning.
• William Leyland – An agricultural expert who becomes mixed up in the lunar drug trade. Narrowly survives after traffickers sabotage his transport from the moon.
• Dare Chin – Assistant Mayor of Labyrinth City, the largest settlement on Mars. Killed during the prologue for Book 3.
• Dr. Dewdney Moreland – A supposed archaeologist whose area of expertise is the relation of objects to the tools that were used to make them. In reality, he is suspected to have stolen several artifacts from the museums where he had conducted his research. Killed during the prologue for Book 3.
• Josepha Walsh – A Space Board pilot who was one of the Free Spirit's underlings, discovered by The Commander trying to carry out a mission for them; she is reformed by him, and no longer serves them. Pilots a Space Board ship that transports Sparta and Blake in one of the books, and later become one of the crew of the expedition to Almathea on board the Michael Ventris.
• Howard Falcon – An inventor-pilot who suffers a terrible accident while flying an airship he helped build and devise the flight of; he survives, but is turned into a cyborg who can do more incredible things than before, such as doing a mission into one of the moons of Jupiter, a mission that the Free Spirit wants to stop.
• Brandt Webster – Deputy Chief of Staff for Plans of the Board of Space Control, and a close friend of Howard Falcon who helps him plan the trip into the Jovian moon.
• Wolfgang Prott – seemingly odious hotelier of the Mars Interplanetary hotel in Book 3 who in reality is trying to stop the Free Spirit on his own, as well as stop the trade in stolen artifacts being directed through the Mars Interplanetary by people like Dewdney Moreland. Is killed by The Orange Man for getting involved.