Episode 4: When Martin advises a patient suffering from migraines to stop cold-water swimming, Mrs. Tishell's attempts to help almost lead to disaster. Martin has his own headaches to deal with when an herbalist sets up shop in the village and then an ex-flame arrives on his doorstep, inviting him to speak at a medical conference in London. Meanwhile, Penhale tries to rekindle his romance with Janice.