Bad Blood by John Carreyrou

Cassie Hobbes joined the FBI’s Naturals program determined to discover the truth behind her mother’s murder. But the truth is far more shocking than she ever imagined: her mother is still alive, and she is being held by a secretive and extremely dangerous organization with a dark history.

As Cassie and the Naturals investigate, they uncover a hidden network connected to murders that have been carried out for generations. With more lives being lost and the threat moving closer to them, the team realizes they are facing something much bigger than a single killer.

Now, the Naturals must race against time to uncover the organization’s secrets before they become its next victims.