Lucky Days — Marshall Thornton

In the ninth book of the bestselling mystery series, a young man wakes up covered in blood and with no memory of the previous night. When hypnotism doesn't help, he turns to private investigator Nick Nowak. Meanwhile, the trial of Outfit kingpin Jimmy English begins. Just as the case begins to unravel an important witness goes missing and Nick must put his other cases, and his home life, on hold while he goes to Las Vegas to find him.