The novel opens with Mona - an orphan and student at the London School of Medicine for Women - failing her Intermediate Examinations.
Rachel asks Mona to conceal her identity as a medical student from the local community and start working with her in the shop.
Mona complies but finds the ruse difficult to sustain after she falls for a male medical student, Ralph Dudley, who is staying nearby.
[1] Mona's middle-class status becomes temporarily strained not only by her choice to pursue a medical vocation, but also by her decision to live with her poor relations.
[2] In the twenty-first century, Mona Maclean has attracted interest from literary critics and historians due to its positive depiction of a female medical student.