Christian Isobel Johnstone was likely born Christian Todd in Edinburgh, Scotland. At age 16, she married Thomas McLeish, a printer; the couple separated about 8 years later and then divorced. In about 1812, she married John Johnstone, a schoolmaster at Dunfermline. They moved to Inverness, where he bought and became editor of the Inverness Courier newspaper. She contributed stories to it and wrote popular fiction for adults and young readers. These included the novel Clan-Albin: A National Tale (1815), The Saxon and the Gaël (1814), and Elizabeth de Bruce (1827). She also wrote nonfiction books on a range of subjects, such as Scenes of Industry Displayed in the Beehive and the Anthill (1827) and Lives and Voyages of Drake, Cavendish, and Dampier, including a History of the Buccaneers (1831). Many of these books were originally printed anonymously. Her highly popular book The Cook and Housewife's Manual (1826) was issued under the pseudonym Margaret Dods. Late in her life, she began to be identified by her real name, in works such as The Edinburgh Tales (1846). She and her husband returned to live in Edinburgh and edited several successive periodicals, including The Schoolmaster, The Edinburgh Weekly Magazine, and Tait's Magazine. She was the first woman to serve as the paid editor of a major Victorian publication.