A mystery is uncovered in a once beautiful Belgian village that played a critical role in the final days of the First World War. A section of trench is unearthed that is not referenced on any military map from the era. And within the trench is a collection of finds: a British Officer’s pair of leather gloves pulled off in a hurry and left inside out; a white silk scarf; a used ampoule of iodine; and an unusual ‘binder’ of canvas and bamboo. The binder is revealed to be a rare Allied Signaller’s kit for sending coded messages back to his gun battery. The trench is identified as a secret forward observation post. Our Trench Detectives’ mission is to find out what befell the Signaller who was stationed there. When they do, they stumble across one of the great lost stories of the War: the biggest explosion ever to rock London, England.