How Rory Thorne destroyed the multiverse

Rory Thorne's thirteenth fairy blessing was to always be able to see through lies, platitudes, and flattery--a curse, actually, to always know the truth. Rory once thought she would inherit her father's throne, but then her brother was born. When her father, the ruler of the interplanetary Thorne Consortium, is assassinated, Rory is married off to the prince of a far away planet. She uncovers a political plot against her betrothed, and Rory must use her thirteenth fairy blessing to stop the plot and rescue her prince.