This is the follow-up story to Zinc about three Jewish siblings John, George and Eva who continue to play different roles to help the war effort in WW2. George trains in Scotland for his SOE mission to Poland to help the fighters in the Secret Army. After his work at Bletchley Park, John is now stationed in Cairo in Egypt working on plans to deceive Field Marshall Rommel about the location of the impending battle, while sister Eva in Hungary is finding life for anyone Jewish getting harder and harder as the Nazis harden their grip over the country. Will the siblings ever manage to get together? They share so many memories, but war keeps them apart. Based on the extraordinary real-life experiences of Sue Klauber's father (Coding at Bletchley Park), uncle (SOE in Europe) and aunt (Resistance), she wrote Zinc and now Cobalt  to illustrate the courage of her Jewish family.