An FBI agent tracks a brilliant serial killer in New York—right back to her own cold-blooded past in a riveting thriller by the Wall Street Journal bestselling author of The Cipher. FBI Special Agent Daniela “Dani” Vega was seventeen when her mother murdered her father. Ten years after Dani’s own damning eyewitness testimony sealed her mother’s fate, she’s starting to have doubts. What if she got it all wrong? A veteran NYPD homicide detective agrees to reopen the closed case on one condition—Dani must help him find a serial killer who’s been operating throughout New York City for the past decade. If anyone can decipher his patterns, and his riddles, it’s a trained codebreaker like Dani. The killer knows this too. And his next riddle—and victim—is meant just for her. For Dani, stopping a killer—and learning what really happened to her father—becomes more personal and more dangerous with each new twist. As secrets of the past are unearthed, the truth could forever change Dani’s life…and the lives of everyone she loves.