Solstice

"Get close to the only son destined to inherit the crown. That is your mission, River Winsted."

River Winsted, a suspended FBI agent, receives an opportunity to be reinstated... under one condition: she must accept an undercover infiltration mission. She must become the lover of Alessandro, the son of her enemy—and her first love—in order to steal information.

"You're not the only one who's changed, Alessandro. I've changed too."

Using the false identity of Lily Gray, River manages to get close to Alessandro and eventually enter his home... a place where, according to him, he had never allowed any of his lovers to step inside. But the deeper she goes into the mission, the more she finds herself irresistibly drawn to this enigmatic man, and it torments her. However, after an unexpected accident exposes her identity, River barely survives. Regretting the moment she hesitated, she swears she will take Alessandro down with her own hands. But the more she follows his shadow, the more shocking secrets come to light...

"There is something I have to do. Just give me a little time. When I'm done... you can stop my breath as much as you want." Alessandro. The only feelings that should ever have been tied to his name were hatred—perhaps resentment. Any emotion other than those should never, under any circumstances, be called love.

(Source: Ridi, translated)