Heat by Stuart Woods

Heat - Jesse Warden, ex-DEA agent, has been framed for the murder of his partner.  Now in the Atlanta Federal Prison, he spends most of his time in solitary because every time he is released into the general population, the other prisoners start a fight with him because he is an ex-cop.  Kipling Fuller has come to the prison to offer a way out for Jesse.  All he has to do is infiltrate a cult in Idaho. Two previous agents have been murdered trying to do just that.  In Idaho Jesse finds that the town is being run by Jack Gene Coldwater.  Coldwater, like he has done to everybody in town, takes over Jesse's life, finding him work and a place to live and of course, letting Jesse know that he is expected to do whatever Coldwater wants him to do.