Al discovers that Bert may not be his father and goes in search of the truth. The members of an odd family with poor hygiene and a passion for taxidermy contract salmonella poisoning, but Martin has difficulty persuading them to accept treatment. PC Mylow's bossy sister arrives in Portwenn and sets up a herbalist business in his flat. However, the doctor is forced to take action when her remedies increase his patients' many ailments.