In Noughts and Crosses , Jack Labinjah was a Cross prison guard who befriended Callum McGregor while he was awaiting to be hung. He returns in Knife Edge to deliver a letter Callum supposedly wrote while in prison to Sephy Hadley. This letter was cruel and told Sephy to forget about Callum. In Checkmate, it is revealed that Callum wrote a second letter which he threw away. Jack died of an illness before he could deliver it and told his daughter, Celine that he would not rest in peace until it got to Sephy. Celine delivered it during Checkmate. Initially Sephy didn't want it but Celine assured her that it was the real letter and that it showed what Callum really thought of her.