This Vicious Hunger — Francesca May

This Vicious Hunger is a dark, gothic fantasy of intoxication, obsession, and two women's desperate hunger for knowledge, whatever the cost.

Thora Grieve finds herself destitute and an outcast after the sudden death of her husband, but a glimmer of hope arrives when a family friend offers her the chance to study botany under the tutelage of a famed professor. Once at the university, Thora becomes entranced by a mysterious young woman, Olea, who emerges each night to tend to the plants in the private garden below Thora's window.
 
Hungry for connection, Thora befriends Olea through the garden gate and their relationship quickly and intensely blossoms. Thora throws herself into finding a cure for the ailment confining Olea to the garden and sinks deeper into a world of beauty, poison, and obsession. Thora has finally found the freedom to pursue her darkest desires, but will it be worth the price?