Agnes Aubert’s Mystical Cat Shelter Book by Heather Fawcett

The story is set in 1920s Montréal and follows Agnes Aubert, a type-A manager of a cat rescue charity. After a magical catastrophe forces her to relocate, she discovers her only available landlord is Havelock Renard, a “failed Dark Lord” and eccentric magician who runs an illegal magic shop out of his basement. Agnes, who is skeptical of magic, must eventually team up with Havelock to protect her shelter when a threat from his past resurfaces.