Martin Danberg was a loyal CIA agent working under Sophia Turner, appearing to serve as some kind of right hand man. Danberg assisted Sophia in bringing Castle and Beckett into their operation to stop a rouge CIA agent, Thomas Gage. He assisted in this operation as best he could and even freed Castle and Beckett from the car trunk Gage locked them in. (Pandora) However, it turned out that Danberg had been framed by Sophia. He had escaped so that he could trail the real turncoat to identify her and prevent her from starting the crisis.