Episode summary 'Knock for Knock', tx. 7/10/1979

Under anaesthetic at her dentist, Claire Stevens gives details of the hit and run incident where her husband was killed, details that she cannot consciously recall. She asks Eddie Shoestring for his help. At Radio West, Eddie is fretting over the script for his broadcast. His boss Don tells him not to worry, but Eddie is unconvinced. Sonia passes on the message from Claire.

Claire tells Eddie how she and her husband were hit by a van six months before. The police were unable to track the culprits down. Under the effects of the gas, she said that the van was white and driven by two men. Eddie interviews the landlord of the only pub for miles around, but gets little help.

Eddie makes his first radio broadcast; after an uncertain start, it is a great success. He appeals for information and is thus able to track down the scrapyard where the van was taken after the accident. He finds an old photograph of an army clergyman recovered from the back of the van. Through regimental records, he identifies the man; the photograph was acquired six months earlier with a bureau by two 'knockers', furniture dealers who trick people to knock down the price of valuable antiques. Eddie finds the bureau in an antique shop run by Barbara Knight.

After another dentist appointment, Claire tells Eddie of a third man who was badly hurt in the accident and whose body was taken away by the men in the van. Through Erica, Eddie's landlady and a barrister, he discovers that a French polisher was found dead six months earlier. Eddie tracks the van, now painted green, to an antiques auction and meets Barbara. She suggests that they go out together, but he sees the van being driven away and gives chase. The two men run him off the road.

Later Eddie receives a tip off as to the van's whereabouts. He arrives at the coast and finds the van, but the two men send his car into the water. They attack Eddie but he is able to get the best of them. He drives the van back to the scrapyard and finds Barbara there. The two men are her sons. She pleads for them, but Eddie reports them to the police. Eddie gets a new car and Don is unamused when the bill is sent to Radio West.