Some Shall Break (None Shall Sleep, #2) by Ellie Marney

This electrifying, chilling sequel to the New York Times bestselling thriller None Shall Sleep focuses on junior FBI consultants Travis Bell and Emma Lewis with a new case that may unravel everything they’ve been working for. 

After a harrowingly close contact with juvenile sociopath Simon Gutmunsson, junior FBI consultants Emma Lewis and Travis Bell went their separate ways: Emma rejected her Quantico offer and Travis stayed to train within a new unit of the FBI Behavioral Science division. But the unit’s latest case is feeling eerily familiar and Kristin Gutmunsson—Simon Gutmunsson’s eccentric twin—reaches out to Travis to send a warning: Emma is in peril.
 
When Travis and Kristin turn up evidence that points back to Daniel Huxton, the serial killer that Emma had escaped, things become more complicated. With a copycat on the loose, Emma returns to Quantico and is thrown back into her past traumas. Compelled to prevent more tragedy—even if it means putting herself in danger—Emma turns to Simon for help once again. But Simon is keeping secrets that could impact their entire investigation. Will the team be able to stop the Huxton copycat before time runs out for his next victims?