Like the twisted strands of mutant chromosomes, an insidious alien conspiracy winds its way through the entire Alpha Quadrant, just as it stretches across several years of Starfleet history - beginning near the very start of Captain Picard's command of the Starship Enterprise! It is only the first year of the U.S.S. Enterprise-D's ongoing mission when a virulent epidemic strikes the populace of Archaria III, endangering the lives of thousands and provoking acts of mob violence against those believed responsible for the spread of the disease. While Data and Natasha Yar team up to uncover the true origins of the virus, Dr. Crusher finds the implacable sickness resists all her efforts to find a cure. The desperate quest for a cure becomes even more urgent when Deanna Troi succumbs to the dreaded plague...again and again.

Gul Dukat rules Terok Nor and all of Bajor with an iron (but compassionate) fist. When Bajorans both inside and outside of his labour camps begin dying of a new disease, his workforce is affected and his management looks bad. Bajoran rebels, convinced that the disease has been inflicted upon them deliberately by the Cardassians, strike back at their oppressors with increasingly desperate measures.But Dukat has an even bigger problem: although it seems medically impossible, the disease that originally targetted only Bajorans may now have begun to kill Cardassians as well. Dr. Katherine Pulaski of the USS Enterprise is allowed to work on Terok Nor to study the virus, which bears a disturbing resemblance to the one that ravaged Archaria III two years before. With the help of a Bajoran resistance fighter named Kira Nerys, will she be able to find an answer before an ailing Gul Dukat is forced to take the ultimate step to protect Cardassia: withdraw from the station and destroy the entire planet of Bajor?

Like the biological weapons they employ, a sinister conspiracy has spread across the Alpha Quadrant and across many years of Starfleet history. Now the mysterious menace surfaces again – to strike at the heart of the Romulan Empire. An artificial virus has infected the entire Romulan ruling family. Ambassador Spock must put aside his efforts at unification to summon his old friend, Dr. Leonard McCoy, who discovers that the only hope for a cure lies with a long lost Romulan heir whose blood and tissues have not been contaminated by the virus. But can the heir be found before the collapse of a ruling dynasty throws the entire Empire into chaos?

Like intertwining filaments of Human and alien DNA, a ruthless campaign of revenge has threaded its way through the galaxy, touching billions of sentient beings - and changing forever the life of Lieutenant Thomas Riker. Tom Riker, an identical duplicate of the Starship Enterprise's first officer, is serving as a Starfleet medical courier when he encounters a group of Maquis renegades, led by a former Starfleet officer named Chakotay. A planet in the Demilitarized Zone, now controlled by the Cardassians, has been stricken with the same deadly disease that has plagued the Alpha Quadrant for years, and only Riker can get the medical supplies the Maquis so desperately need. But the Cardassians would rather destroy all life on the planet than risk letting the epidemic spread!

Like a lethal bacillus coursing through the bloodstream of the galaxy, a fiendish master plan has spread death and terror across the 24th century – until two heroic captains risk everything to stamp out the evil at its source! For more than a decade, since the very beginning of the Starship Enterprise's mission, unknown enemies have unleashed a string of deadly biological weapons throughout the Alpha Quadrant, inflicting ghastly epidemics upon the Romulans, the Cardassians, the Bajorans, and even the Federation. Now, at long last, Captain Jean-Luc Picard joins forces with Captain Mackenzie Calhoun of the Starship Excalibur to track down and confront the hidden architects of the plagues – and avenge the deaths of thousands!

The final book in this great saga is set 30 years ago—stardate 2350 — when a young Captain Picard commanded a ship called Stargazer and first encounters the deadly foe that late threatens the existence of the Alpha Quadrant.