Martin learns that he is under investigation for rude and condescending behaviour with the end result that he may have to attend a 2-week course to improve his people skills. Pauline advises Martin that he will have to find a new receptionist, as she is returning to university to study nursing. Auntie Joan is accidentally shot in her foot by Colonel Gilbert Spencer, who is excited about the rare birds nesting in the cliffs above her home. Bert Large sees the nestings as a golden opportunity to run guided tours in a borrowed police van. Al Large, meanwhile, decides to strike out on his own as a plumber, to prove his worth to Pauline, whom he asks to move in with him. She discovers he forgot to mail her university application.*Louisa's father Terry Glasson (Kenneth Cranham) suddenly re-appears in the village, accompanied by his friend, Jonathan Crosier (Chris O'Dowd). Terry had left the village under a cloud when he was accused of stealing money from the lifeboat fund, but he has always maintained his innocence and Louisa remains his staunchest defender. Things get serious when Jonathan stops taking his medication and hallucinates that his brain is receiving radio communications from an unknown source . He takes Martin, Louisa, Terry and Pauline prisoner, demanding Al pick up a shipment of explosives, so he and Terry can carry out a planned robbery. When Al and Martin rescue an injured bird egg thief from a cliff, Jonathan believes the eggs were transmitting the radio signals.

Martin believes Louisa may be anaemic after she passes out in front of her class. Allison Lane's (Debbie Chazen) daughter Delph (Jaimee Colmer) is treated for hyperactivity, but the cause is later suspected that she's been taking her Mum's diet pills.[14] After the horror and shock of discovering his fiance Julie's secret, Constable Mark Mylow has left ? PC Joe Penhale (John Marquez) arrives in Portwenn to replace him, arousing attention from the doc, who discovers him unconscious at the wheel of his police car. Louisa becomes Martin's patient.[15] Titled Tick Tock in American release.

Bert Large abandons his plumbing business in favour of running a restaurant, but neglects to get a licence for serving alcohol. Following the restaurant's opening, several cases of food poisoning occur with Louisa being one of the people affected.[15] Poppy (Emily Head) fills in at the doc's office while Pauline takes a class for certification as Martin's lab assistant. Mandie (Daisy Head) sees the doc for a developmental crisis, which he handles with unusual tact. Mick Mabley (Joseph Morgan) becomes Bert's new chef.[16] Titled The Morning After in American release.

Anthony (Karl Theobald) and Terri Oakwood (Amy Marston), and their undisciplined son Sam (James Cronin) who vandalizes vehicles, move in next door to Louisa causing problems for her, Martin and the local people. PC Penhale has developed agoraphobia.[15] Lonely widow Mrs. Avirell (Eileen Essell) makes repeated visits to Martin's office for a habitual cough. Her cat TomTom has disappeared, and unbeknownst to her, has been sleeping with Sam. Both Sam and Mrs. Avirell are diagnosed with tuberculosis. Titled Love Thy Neighbor in American release.[17]

Hotel owner Carrie Wilson (Louise Delamere) has her sights on Martin much to Louisa's chagrin. Martin later accidentally runs over and kills Wilson's dog with his car. Joan has an admirer in painter Edward Melville (Justin Salinger), who is 30 years younger than she. Martin walks in on them having sexual intercourse in her home. He and Joan later quarrel over his objections to the relationship. Melville later collapses at Wilson's hotel, diagnosed by Martin as having overdosed on medication prescribed for erectile dysfunction. Al Large returns after a lengthy trip to Africa, telling Martin he was robbed of all his possessions during his trip. Pauline finds Al collapsed on the floor of his apartment. Martin diagnoses him with sleeping sickness, the result of having been bitten by Tsetse flies while in Africa.[15][18]

Martin takes Pauline's mother Dawn (Denise Black) off all medication and prescribes a change in diet. Louisa and Martin attend a charity concert together, and when Louisa pulls him beneath a tree for a kiss, he ruins the moment by coldly diagnosing her gesture as mood swing behaviour. Louisa realizes they are going nowhere as a couple, and ends their relationship. Auntie Joan insists Martin can work at being a more understanding personality, but he insists he is unable to change and refuses to, " ... talk rubbish and smile all the time." Bert Large quits buying his produce from Auntie Joan, who believes they had a verbal contract.*Pauline's gambling addiction finally comes to a head after she is so distracted that she mixes up patient records, and her scooter is repossessed. Al Large insists to Martin that Pauline fully paid for the scooter with her gambling winnings. After an explosive confrontation in Martin's office with Dawn over Pauline's using her credit card for her gambling, Martin orders her mother out of the office and insists Pauline get professional help with her addiction or be fired from his employ. He makes her return money that Al loaned her to get her scooter back.*Louisa's friend Holly (Lucy Robinson) sustains a back injury walking with Louisa. While recuperating at Louisa's apartment, Martin pays a professional visit and awkwardly, following Auntie Joan's advice, tries to express sympathy for the patient. Martin and Louisa argue over his attempt as unfeeling lip service. Martin resuscitates Holly after she collapses on the floor, while Louisa watches in amazement and expresses her admiration for his skills. The episode ends with Martin proposing to Louisa, telling her he can't imagine life without her. She immediately accepts his proposal.

Originally aired during the week of Halloween in 2007. The news of Martin and Louisa's engagement spreads like wildfire through Portwenn, and Bert Large asks to cater the wedding. Martin wants to be married in a church wedding. The divorced PC Joe Penhale offers his advice on handling women. Pauline asks to be a bridesmaid. A mysterious respiratory infection breaks out in the village. Martin becomes concerned about patient Beth Sawle (Thelma Barlow) who has a fungal infection in her lungs and lives with her domineering and sinister sister Janet (Irene Sutcliffe), a biochemist who concocts potions and pills in a basement laboratory. Pauline tells Martin that Janet is called "the Black Widow" and is alleged to have murdered her colleagues. Janet says she was fired from her position for, "a difference of opinion over procedure", and doesn't want Martin snooping around their home. Beth is brought into submission by Janet's controlling personality and threats of the consequences if she doesn't follow Janet's orders.*Pharmacist Mrs Tishell, who is found passed out and slumped over her counter, is awakened by Martin and tells him that Beth has filled no prescriptions with her. When Martin delivers Beth's antibiotics medicine to her home, he and sister Janet, who has been growing mushrooms in her basement, have an argument about her overbearing interference in his medical care for Beth. After he leaves, Janet later takes away Beth's medicine, insisting that Beth take only her concoction brewed from her home-grown mushrooms. Beth invites the letter carrier Dave (Tony Maudsley) in for a cup of tea, and Janet berates Beth for doing so, hinting that she might have Beth put away in a hospital.*Bert makes an office visit to Martin for a chronic cough, and says he feels like something has crawled into his ear. Dave later collapses in Martin's office, and Mick Mabley is found unconscious in Bert's restaurant kitchen. Martin tells PC Joe Penhale the epidemic has been caused by spores and fungus. Penhale compares the situation to Invasion of the Body Snatchers. Al Large is concerned about his finances, and his increasing cough spasms. Martin finds the pills Janet is forcing Beth to take, and goes to the basement lab of mushroom cultures and concoctions. He has an argument with Janet and accuses her of being the source of the illness outbreak in Portwenn, calling her a "spooky old bat". While making wedding plans at Bert's outdoor restaurant, Martin gives Louisa nasal strips to keep her from snoring next to him at night.

On the day of their wedding, Louisa's pregnant bridesmaid Isobel (Amanda Abbington) is hit in the eye with a party popper and has to wear an eye patch. The local florist gets arrested and his shop shuttered. Roger Fenn (Jeff Rawle) is set to give the bride away, and helps Martin select the hymns. Bert Large has to make contingency plans for catering the wedding, after the water pipes burst on the pavement. Martin suggests the vicar the Rev. Counter (David Ryall) has a drinking problem and later catches him with a bottle of whisky and tries to wrestle the bottle out of his hands. The vicar ends up in hospital after falling over and fracturing his hip. Martin asks neighbouring vicar Mr Porter (David Bamber) to be the replacement, even though Porter has become disillusioned and cynical about weddings. Martin pays a high price for his services, having to perform a medical procedure on Porter's pet pig. PC Joe Penhale breaks the door on the florist shop so Auntie Joan can get the flowers for the wedding. Bert and Al's catering tent collapses. Louisa's maid of honour goes into labour outdoors on a hill, and Martin delivers the baby daughter. Louisa and Martin decide not to get married, leaving everybody else waiting in the church.[15] Titled In Sickness and In Health in American release.[21]