For you English-speakers who obviously cannot read the book ! It's summarized very quickly, just to give you an idea what the book talks about.

Lyen is found in the forest, during a raging storm. She is pregnant, and about to give birth. She is "rescued" by militaries and employees from the environmental sciences department (Ludméa is the one that finds Lyen). Lyen, as well as Ludméa, are then taken to the department of military science, under the direction of Ruan Paso. A virus is suspected, so Ludméa, as well as Lyen, are put under quarantine.
Lyen, by then, has given birth to twins, boy and girl, with pale skin and strange blood properties. The babies don't seem as interesting as their mom to the militaries : Lyen is red-haired, she has six fingers in each hand, she has slit pupils (no one knows why), and gills behind her ears.
Ruan Paso begins to have very strong feelings for Ludméa, who reminds him of somebody else (first girlfriend named Katrin). Problem is : he is engaged to famous scientist Ylana Schmidt, a beautiful and very jealous woman.
(it's really, really summed up)
On the other side, Lúka lives with his twin sister Line. Their father is an horrible man, who beats them and made them suffer during their whole childhood. Lúka has a "mission" involving Lyen and the babies. Several times, he interacts with Ruan Paso. They really don't like each other. However, they work together to make Lyen's body disappear as she dies of a strange illness (virus) leaving her children alone. Ludméa takes it personaly to care for the kids, but when she learns the truth about Ruan's relationship to Ylana, she doesn't want to hear from him anymore.
Back to Lúka and Line : Lyen is not dead, but Lúka's father is (Lúka killed him). Line is pregnant with Lúka's child (yes), and they need Lyen as a surrogate mother for a "project" involving embryos.
(additional info : Lyen was Lúka's captive before she managed to escape and arrived on Ruan and Ludméa's planet. Lyen herself was captured from another planet and another time by Lúka's father)
Lúka is a well-known informaticien, who built a fantastic OS called Z'arkán. He is in partnership with his best friend William, CEO of Microsoft-in-the-future ^^ (this will be changed in the published book, don't wanna be sued ^^). They launch the new version of Z'arkán, and the same night, Line gives birth to a baby boy, whom she named after her father (strangely enough...).
Back to Ruan and Ludméa : Ruan drops girlfriend Ylana two weeks before marriage and begs Ludméa to forgive him for lying to her. They finally end up together, so all is well that ends well (not really, that's why it's only the beginning ^^).
Any question ?

Now, the characters : (for physical infos, please check Album and Persos)
Ludméa is cheerful, always in a good mood. Very natural, sensitive girl. She is around 22. She is honest, a bit naive, even.
Ruan is quite arrogant, very selfish, self-centered. He kinda looks everyone down, except Ludméa. That, at least, is what he shows at work. Other than that, he is also a very sensitive guy, very kind, unsure, lacking self-confidence. He is 34.
Lyen is tourmented, scared of her new surroundings, but she is obstinated and willing to do everything to save her children. She hates Lúka and Line, and doesn't like Ruan very much either. She loves Ludméa, whose kindness reminds her of her own sister, Nato, who died, killed by Lúka's father.
Line is also very tourmented, moony, sometimes cheerful and sometimes very sad. Also very obstinated. Most of the time, she lets her brother take all important decisions, but sometimes, she is the one that takes the lead. She seems fragile, but in the end, she is at least as strong as her brother.
Lúka is the main character of the story, even if it's not really shown in this first part. Like her sister, he is tourmented. As a kid, he was beaten by his father, quite often. He always tried to make him proud of him, by doing everything to please him, but his father didn't care. He hates Lyen, and he doesn't really understand why. He is sarcastic and arrogant with everyone except Line. He seems very self-confident, but he really is vulnerable and unsure. He resents the missions his father made him carry out, but on the other end, he still wants to fullfit them, even after his father's death.

I hope that's enough ! If you have any questions, feel free to ask them !