Terry Ainsworth is more interested in train spotting than going to school, and he is happy when his father Eddie takes him on a train ride. Little does the boy know that his father, who is fresh out of jail, is planning to steal a lot of fur coats and he wants to check out the railway line for the best spot to do it. It does not matter to him that his wife Molly is working at the company which produces the fur coats. Greengrass is doing some gardening for Mr. and Mrs. Dobson when he finds some old, Roman coins. Convinced there are more where they came from he rents an excavator to do some serious digging for them while the Dobsons are away for a couple of days.