The Wild One by Nick Petrie

Peter Ash is finding it difficult to keep his PTSD at bay. When Catherine Price asks Peter to travel to Iceland and bring her young grandson, Oskar, home, he agrees to take on the job, even though he knows others have failed at the task. Oskar was taken to Iceland by his father, Erik, after Oskar's mother, Sarah, was murdered in Washington D.C. Soon after his arrival, Peter learns that the U.S. government is ordering him to be on the next plane back to America in two days time. Peter wonders why the government is getting involved, and it's his nature to not want to follow any authority. The Wild One takes Peter through Iceland's harsh environment on his quest to find Oskar and keep him safe. A great read-alike for Lee Child and those looking for a new thriller series. However, newcomers are advised to start at the beginning of the series with the book, The Drifter.