I Spy

Description for I SPY by Jacey Ford:

Former FBI special agent Aimee Devlin has a special talent for blending into the woodwork. The mastermind behind a fledgling corporate services firm, Aimee plans to use the skills she learned while with the FBI to make her and her partners rich. When she takes a job to find out who is selling an aerospace company's top-secret designs to a competing firm, she never expects to end up engaged to a wealthy gunrunner while spying for the U.S. government and lying to save her life.

This is #2 in Partners In Crime Series.