"Never stay, Lacey. Promise me. Promise me right now, that whenever things go bad in life, you will run. Never, ever stay." 

Lacey Monroe loved by the mantra her mother instilled in her.  

When things got bad, when things got dangerous, when there was a chance that she would get hurt, she did what her momma said. She ran. 

When she meets Roam Cooper, the Vice President of the Mayhem Motorcycle Club, for the first time in her life, Lacey considers staying.

And then right before her eyes, her world implodes, and she runs again.