While a Soviet project for an orbital bomb threatens the world balance, Francis Mareuil, an aerospace engineer, is sent East to recruit the scientist whose research made this bomb possible and falls for his daughter, Luydmila Golubeva.
In East Berlin, Francis finds out that Boris is under the constant surveillance of the Stasi. He bonds with Lyudmila, convinced that she can get him access to her father, but oblivious to her ties with the KGB.
In Moscow, Boris heads the launch of a space probe that turns into a fiasco and is placed under house arrest. Meanwhile, Francis tries to find a way to save Lyudmila by bringing her West, even if it means risking it all.
Lyudmila is back in Czechoslovakia with her wounded father, and in danger: the KGB is tracking her down. Francis tries to understand what Boris found in the probe and retreats further and further away from his family.
Lyudmila is alone and stuck in Czechoslovakia. Francis reconciles with his wife and takes part in a mission co-speared by the SDECE and the CIA, with a common goal: to contact Boris.
While investigating Charles Contignet, Anne makes a troubling discovery. Hunted by the KGB, Lyudmila hides with a Czech family. There is only one way out for her: to contact Francis and ask him to come save her.
In Czechoslovakia, Francis jumps through hoops to find Lyudmila. As they try to get back West, Yemelin and his henchmen chase them down. Anne finds a top-secret document and is now in danger. She must flee.
As the orbital bomb is about to crash, Francis, Lyudmila and Anne risk capture and death. Yemelin, through powerful allies in France, will do anything to get the numbers back, as well as the list.
