The Brotherhood of the Rose by David Morrell
They were orphans, Chris and Saul - raised in a Philadelphia school for boys, bonded by friendship, and devoted to a mysterious man called Eliot. He visited them and brought them candy. He treated them like sons. He trained them to be assassins. Now he is trying desperately to have them killed. Spanning the globe and full of heart-stopping action, The Brotherhood of the Rose is an astonishing novel of fierce loyalty and violent betrayal, of murders planned and coolly executed, of revenge bitterly, urgently desired.