The Lyon's Puzzle (The Lyon's Den Connected World)
Sandra Sookoo

Besieged by rumor and innuendo... Mrs. Adriana Roberts née Stapleton, eldest daughter of Baron Kentwood, is a widow accused of killing her reprobate husband. In the scandal that followed his death, she returned home, only to dance attendance on her much younger and more beautiful sister, for the chit still has a chance of a good match. But when that sister’s hand is lost at a card table to the Worst Man in London, she has to do something.
The past has a habit of retaining a grip... When the owner of the Lyon’s Den arranges a devious marriage between them, they have no choice but to comply. As Montague acts like an enraged beast, Adriana vows to keep the union as a marriage of convenience despite the intense attraction present. But when understanding chips away at their defenses, romance might have a chance if they choose to trust after years of disappointment and hurt instead of locking themselves away into darkness.
Or else Mrs. Dove-Lyon will make certain they get exactly what they want...