Young Deck Officer Arthur Hawkins (Thomas Brodie-Sangster) leaves his pregnant wife Maud (Nathalie Emmanuel) to join the San Demetrio. Shipping Manager Robert Dodds (Brian Cox) promises to keep an eye on Maud. Loading a vital and highly volatile cargo of Texas aviation fuel for the Royal Air Force, they set off in a convoy of other ships for England. On board is an American, Oswald Preston (Blair Redford). In the High Court in London, a court case starts.