The Rhythm Section by Mark Burnell

Now a motion picture, from the producers of the James Bond film series, starring Jude Law and Blake Lively.

She has nothing to lose and only revenge to live for
She thought her life was over…
Stephanie Patrick's life is destroyed by the crash of flight NE027: her family was on board and there were no survivors.

Devastated, she falls into a world of drugs and prostitution – until the day she discovers that the crash wasn't an accident, but an act of terrorism.
Filled with rage, and with nothing left to lose, she joins a covert intelligence organization. But throughout her training and operations she remains focused on one goal above all: revenge.