Night Fall (Quantico Files‪)‬

Now that Alexandra "Alex" Donavan is finally free of her troubled upbringing, she's able to live out her childhood dream of working for the FBI. But soon after she becomes a member of the FBI's elite Behavioral Analysis Unit, authorities in Kansas and Missouri contact them about bodies found on freight trains traveling across the country—all killed in the same way.

Alex never expected to be forced to confront her past in this new job, but she immediately recognizes the graffiti messages the killer is leaving on the train cars. When the BAU sends her to gather information about the messages from her aunt in Wichita, Kansas, Alex is haunted by the struggles she thought she'd left behind forever.

In a race against time to solve the case while battling her own weaknesses, Alex must face how far she'll go—and what she's willing to risk—to put a stop to the Train Killer.