Jen Barber (Katherine Parkinson) is captivated by a pair of shoes she sees in a shop window, despite the fact that they are several sizes too small for her big cheesy feet. She returns to her work colleagues Roy Trenneman (Chris O'Dowd) and Maurice Moss (Richard Ayoade) at Reynholm Industries, where a meeting has been called by their boss, Denholm Reynholm (Chris Morris). Denholm is 'declaring war' on stress, and has organised a stress class with leading 'stresspert', Dr. Julian Holmes. He also warns his employees that anyone experiencing stress at the end of the day will be fired. Roy and Moss attend the meeting due to the attraction of a free buffet, while Jen decides to leave the building to buy the shoes that she has been thinking about ever since she saw them.

At the shoe shop, Jen insists that her feet are small enough to fit into the shoe and, after a battle with the shop worker, she manages to force the shoes on, causing her extreme pain. Meanwhile, at the stress meeting, Roy and Moss are causing havoc by bothering Dr. Holmes, so much so that the relatively calm doctor is sent into fits of rage, abruptly ending the meeting. Roy and Moss return to the basement, where Moss builds a replica of a stress measurement machine he had seen at the stress class and tests it out by stabbing in between his fingers with a screwdriver, sending his stress levels rocketing.

However, the office is set on fire because of Moss's negligence in using a soldering iron to make the stress machine; but, despite memorising it earlier, Moss cannot remember the new number used to call the emergency services (0118 999 881 999 119 7253). Moss attempts to extinguish the fire himself, but after setting the extinguisher itself on fire, he resorts to sending an email to the emergency services. Meanwhile, Jen is struggling to cope with hiding the fact that she is in extreme pain due to her new shoes and removes them, revealing her extremely deformed feet. She visits a doctor, who forbids her from wearing the shoes again. Because she threw away her old shoes, she is forced to return to the office barefoot, disturbing many of her co-workers with her completely mangled feet.

Meanwhile, Denholm has organised Reynholm Industries to merge with the successful Japanese company, the Yamamoto Corporation. Both companies have exchanged gifts, Mr. Yamamoto has given Denholm a ceremonial sword, while Denholm has given Mr. Yamamoto a ‘massive pair of Doc Martin’s. Mr. Yamamoto, overcome by such large shoes, begins stomping around the office.

Coincidentally, Jen is walking past, and Mr. Yamamoto accidentally stamps on Jen's injured feet. Jen suffers extreme pain and begins violently swearing at Reynholm Industries' new business partner. Mr. Yamamoto is shocked by Jen's sudden outburst and leaves, cancelling Reynholm Industries' merger with the Yamamoto Corporation. Denholm is very angry and commands Jen to return to her department, as he suspects her of suffering from stress and will fire her if he finds this is true.

Meanwhile, Roy meets Dr. Holmes again and asks if he could try the stress machine. Dr. Holmes has not forgotten the chaos at the meeting and attacks Roy, however, Roy manages to escape with the stress machine in tow. He returns to the basement and discovers the fire that Moss had caused. Moss remains calm and assures Roy that he has sent an email to the fire department. Jen returns and commands Roy to help her put on the shoes before Denholm arrives. While trying to put on the shoes, Roy is stabbed by the high heel and is sent into fits of agony. Roy recovers in time to mask the fire by putting the frame of a computer screen in front of the flames, making it look like a fire-themed screensaver. Denholm arrives to test Jen’s stress levels and, without noticing the fire, grabs Roy’s stolen stress machine and measures Jen’s stress levels. He is disappointed to find that she is perfectly calm, and leaves the basement. Jen then collapses due to her injuries with the shoes and Roy follows suit due to blood loss from his stab wound and the fumes from the melting monitor. Moss, meanwhile, is knocked unconscious when the door bursts open to reveal the fire department who Moss emailed earlier.

This will be an eventful event