Although it is set entirely in the 16th century, in Spain and England, it is a science fiction story revolving around the activities of a group of immortal cyborgs, individuals who appear human but have been transformed by high technology.
Mendoza is a cyborg, who, like others of her kind, has been rescued from certain death as a small child and turned into an immortal machine, then made to work for "The Company."
American illustrator Michael Koelsch painted the cover art of Baker's first three novels in The Company series, beginning with In the Garden of Iden.
By travelling far into prehistory, the company creates its own immortal cyborg agents, who then have the mission of preserving cultural artifacts and other valuable items for sale in the 24th century.
Usually these items are hidden in safe places, but in the case of extinct species, for instance, they are kept in secret Company caches run by the cyborgs.
Mendoza and her companions journey to England, to the county Kent estate of Sir Walter Iden, who keeps a collection of exotic plants in a walled garden.
Alexander Iden and Jack Cade are both historical figures, as well as being characters in William Shakespeare's play, Henry VI, part 2.
Mendoza tells how she is snatched as a child from the Inquisition in Spain, having first been sold by her real parents to some 'noble Christians' who want her for pagan rites, but are instead arrested.
This she does, and settles in for a long stay, having decided that the Garden is full of unusual plants that will take years to catalogue.
Nicholas, it turns out, has a dark past, having been a member of an ecstatic Christian cult that practised sexual freedom.
Deciding that the cult leader was simply exploiting his fellows, he broke away and began preaching radical ideas, for which he was arrested and put in chains.
As she matures, she finds she emits "Crome radiation", a psychic field which can have unpredictable effects on time and space.
(In a later Company story, we learn that Joseph caused the tests to be fudged because otherwise Mendoza would be tortured to death by the Inquisition.)
Old Sir Walter Iden, having been given rejuvenating treatments by Joseph as payment for their stay, decides to sell the estate and move to London.
Though he talks his way out of the immediate situation with his usual skill, he is eventually found out by Nicholas, who sees him doing self-repairs to his internal machinery.
[2] Publishers Weekly found it to be "lively" and an "agreeable read" for fans of time travel stories, with "robust and detailed" characters and setting, but faulted its pacing and its "unusually far-fetched" premise.