Rise of the Wolf is the second book in Nielsen’s Mark of the Thief series. The series is set in ancient Rome, and continues the story of Nic Calva, a former slave who steals a magical artifact in the first book before discovering his own magic as well as connections to very powerful Roman leaders.
Both books of this series are complex and entertaining. Rise of the Wolf seems to be in the border area between MG and YA. Though I’ve seen it listed as both, I thought Nic was a little young in the first book for it to by YA, but the violence and overall theme of the series so far fits in better with YA.