Northern Spy by Flynn Berry

Tessa lives with her young son Finn outside of Belfast and is a producer at the BBC. One day, her sister Marian is seen participating in an armed robbery. The police tell Tessa that Marian is a member of the IRA. Tessa doesn't believe it's true, since both she and Marian are against all the violence that has occurred over the years. What if the evidence the authorities have is real? Could Marian really have put Tessa and Finn in danger? Northern Spy keeps the reader on the edge of their seat as Marian's decisions have serious repercussions for everyone.