The fears of generations are realized in a brilliant flash in the shadowy wastes beyond Jupiter. From a mysterious array appear two alien ships, their vicious intention all too clear as they fall upon a pair of Terran ships battling over ownership of the enigmatic discovery.They come from Gliese 581g where, in 2008, a message of peace was sent. They are an avenging force, unleashed to deliver a terrible retribution upon a trusted industrial magnate and secret liaison who is now determined to steal their technology. The aliens are powerful, technologically advanced by many decades, and determined to end the human threat.Captain Ian Walker, recently retired from NASA and at the end of a career that saw him removed from his last command in disgrace, is called back because of his rare combat experience and is given command of the elderly monitor, NASS Centaurus. Captain Corina Sacramento, her crew exhausted and her ship worn out after completing a seven month asteroid survey for the South American Space Agency is waylaid from her return mission to Earth and redeployed to the Jovian moon of Himalia. Commodore Sorscha Cameron, former commander of the European cruiser, Indomptable, is given a field promotion and the impossible task of holding the Jovian System.Their mission is simple – they are to join the United Nations task group assigned to protect the Terran interests in the Jovian System and shield the excavation of an alien spaceship buried in the ice of Europa. As the Gliesiuns amass a powerful force, and the spacefaring nations of Earth, Luna, and Mars argue over control of defences, all three must fight feelings of self-doubt and fear to rally their task group to defend the future of mankind in the outer solar system.