The Science of Power (Emerson, Ru. Night-Threads.)

The spellbinding conclusion to the Night-Threads series begins as a woman of craft, blessed with an overwhelming courage, takes a great risk to combat a traitorous evil that threatens all of Rhadaz. The world remains under the cold-blooded rule of an emperor gone mad, and it is only through the science of power that peace can be restored. But as her family finds the source of their world's many secrets--Chris with the dreaded drug Zero, Robyn finding happiness with Aletto--it is Jennifer's who finds herself readying for one last battle. Whoever holds the power of the sword may just triumph over the devastating power of dark magic.