Star Trek: Double Helix
Star Trek: Double Helix is the omnibus edition of the miniseries Double Helix. It contains the following novels:

 
 Vectors 
 Red Sector
 
 Double or Nothing 
 The First Virtue

Summary
From the book jacket
Like a strand of mutating DNA, a deadly conspiracy winds its way through the Alpha Quadrant, even as it stretches across several years of Starfleet history. This special omnibus volume contains the entire bestselling saga – by some of Star Treks most popular authors: Book One: John Gregory Betancourt Deanna Troi's life is endangered by a mysterious plague that threatens to spread throughout the Federation and beyond! Book Two: VectorsDean Wesley Smith & Kristine Kathryn RuschOn the Cardassian space station known as Terok Nor, Dr. Katherine Pulaski struggles to heal the planet Bajor! Book Three: Red SectorDiane CareyAn elderly Dr. McCoy reunites with Ambassador Spock to save the Romulan royal family – and a new generation!Book Four: 
John Vornholt

Lieutenant Tom Riker joins forces with the outlaw Maquis to rescue a world in peril!

Book Five: Double or Nothing
Peter David

Along with Captain Mackenzie Calhoun of the Starship Excalibur, Jean-Luc Picard tracks the deadly contagion to its source!

Book Six: The First Virtue
Michael Jan Friedman & Christie Golden

Years before commanding the U.S.S. Enterprise, a young Picard must prevent a war – and witness the secret origin of a diabolical threat that would someday menace all he cares for!

Double Helix