In 1945, a nameless girl escapes from a displaced person camp in Kalyros, Greece. She remembers nothing from her short past and wanders through post-World War II Mediterranean, the Middle East, and regions of North Africa, where she learns to survive the hard way. She befriends Lob, another wandering refugee who is a Jewish Hungarian scholar from Budapest. He gives her an education and a first name: Modesty. Some time later Modesty creates her last name after Blaise, Merlin’s tutor from the Arthurian legends. When Lob dies is unclear, other than it being prior to her going to Tangier. In ‚The Xanadu Talisman‘ it is mentioned that Modesty has left Lob at a village to recover from a wound; she goes alone to sell a car tyre. In 1953 she takes control of a criminal gang in Tangier from Henri Louche and expands it into an international organization called the Network.
During the years that she runs the Network she meets Willie Garvin. Despite his desperate lifestyle, she sees his potential and offers him a job. Inspired by her belief in him, he pulls through as her right-hand man in the Network and becomes Modesty’s most trusted friend. Theirs is a strictly platonic relationship, based on mutual respect and shared interests. He always calls her „Princess“, a form of address only he is allowed to use. Other members of the Network call Modesty „Mam’selle“ (as in the French term „Mademoiselle“ or „Miss“). Though their relationship has no sexual element, Modesty’s various lovers often feel jealous of Garvin – as he is the only man who remains part of her life, while lovers come and go. By the same token, some of Willie’s girlfriends are initially jealous of Modesty, but later come to understand how the dynamic between them works (such as in the case of Lady Janet).
She obtains British nationality by marrying and divorcing an Englishman in Beirut; the husband (James Turner) dies a year later of alcoholism. Having made a point of not dealing in secrets belonging to H.M. Government, when she feels she has made enough money, she retires and moves to England and Willie Garvin follows suit. Bored by their new lives among the idle rich, they accept a request for assistance from Sir Gerald Tarrant, a high-ranking official of the British Secret Service. This is where the story really begins, although it is treated differently in the first comic strip and the first book. (See note in Differences between Comic Strip and Books, below.) Modesty’s fortune is estimated at 500,000 pounds as of 1963 (over 8.84 million pounds in 2020). She lives in a penthouse in London overlooking Hyde Park, and also owns a villa in Tangier and a cottage two miles from Benildon, Wiltshire. She is 5 feet 6 inches (168 cm) tall and weighs 120 lbs (54 kg) as revealed in La Machine.
Many of her adventures are based on capers in which she and Willie Garvin become involved as a result of their association with Tarrant. However, they may also help perfect strangers or fight various eccentric villains in exotic locations of their own volition if the cause fits their values; „ghosts“ from their Network past also emerge to haunt them from time to time. Although Modesty and Willie will not hesitate to kill if necessary, they avoid deadly force whenever possible, often relying upon their extraordinary physical combat and weapons skills. There are many occasions in the comic strip and novels where the two decide ahead of time whether to use deadly force („for keeps“) or less-lethal methods („for sleeps“) depending on the level of the perceived threat.
A dumbbell-shaped yawara stick, or „kongo“ as it is called in the Modesty Blaise books and comic strips
In Willie and Modesty’s fights there is a great emphasis on unarmed combat and unusual weapons. Modesty’s weapon of choice is a „kongo“ or yawara stick and as for firearms she begins by preferring the Colt .32 revolver and Mab Brevete .32 ACP auto pistol, although in later books she switches to carrying a Star PD .45 auto pistol. Willie’s preferred weapon is the throwing knife, of which he usually carries two. Many other strange weapons (such as the quarterstaff, épée, blowgun, and sling) and unexpected fighting techniques are also featured.
In keeping with the „floating timeline“ spirit of other long-running comic strip and literary characters, Modesty and Willie generally do not age over the decades, with Modesty always being depicted as being in her late twenties and Willie eight years older. The only exceptions to this rule occur in the comic strip origin story, „In the Beginning“; the 1996 short story collection Cobra Trap, the final Modesty Blaise book, which contains five stories that take place where Modesty’s age moves from 20 to 52 (approximately); and the 2003 film My Name Is Modesty, which is a prequel depicting Modesty in her late teens.