When his famously precise secretary, Miss Lemon, makes three uncharacteristic errors in a single letter, Hercule Poirot knows something is wrong. The cause is her sister, Mrs Hubbard, who manages a hostel for students at 26 Hickory Road and has been troubled by a baffling outbreak of petty theft. The stolen and damaged items make no sense as a pattern: a stethoscope, an old pair of flannel trousers, a box of chocolates, a slashed rucksack, a light bulb, and a diamond ring later discovered in a bowl of soup. Intrigued by the sheer eccentricity of the list, Poirot agrees to visit the hostel and address the residents, a mix of young men and women from across the world pursuing studies in London. Beneath the surface camaraderie, he senses tension, concealment, and motives that have little to do with simple kleptomania. When one of the students is found dead, the trivial mystery turns deadly, and Poirot must untangle a web of secrets among people who all have reasons to hide the truth. Working alongside Inspector Sharpe, he applies his methodical reasoning to a closed community where everyone is a suspect and the smallest detail may carry the heaviest meaning.