Vow of Deception by Rina Kent

Britt's take

High-tension Russian mafia romance with real mystery and suspense—impossible to put down. I binged this and then the rest of the trilogy without stopping. Survival is part of the dynamic, the leads are morally grey, and the plot reveals will keep you on your toes. Figuring out who's trustworthy is half the fun. Spoiler: No one is. If you want your dark romance to come with a genuinely gripping plot, this is the one. Brace yourself for a cliffhanger and prepare to read all 3 books.