6x3 - Doc Martin

A stranger stops dead in his tracks when he sees Ruth in the village, and later he spies on her when she is having a coffee with Caroline. Ruth is not sure why, but she starts feeling uneasy. One of Louisa's pupils blames an upset stomach on a meal she ate at Bert's restaurant and writes about it in the school magazine. Bert and Al are furious, and they go to see Louisa wanting something to be done.