Leonard gets caught up in an armed robbery at the village post office, and manages to identify the masked culprit. Geordie takes no chances when going to arrest the criminal, who has a record of similarly violent crimes - but is surprised to discover that the suspect has been murdered. Meanwhile, a second robbery occurs, carried out by a man and a woman who have adopted the dead robber's trademark of disguising himself with a gas mask. Back at the Vicarage, the atmosphere is tense between Sidney and Amanda.