Curled Up with an Earl by Amy Rose Bennett

Miss Lucy Bertram is content to spend her days writing scientific articles or curling up with a Gothic romance novel. Indeed, she’d rather stick a hatpin in her eye than attend a ball. But when her father, the eccentric botanist Sir Oswald, insists she accept the suit of a wealthy but stiffer-than-a-poker industrialist to save the family from penury, Lucy decides to act. She’s certain her disowned brother, Monty, will take her side. But first she must find him in St. Giles’s cutthroat rookeries.
A covert agent for the Crown, William Lockhart, the Earl of Kyle, is on the hunt for a ruthless killer determined to destroy the Linnean Society. Sir Oswald, a botanical poisons expert, is the prime suspect. Posing as a groom in the baronet’s household, it shouldn’t take Will long to unearth the evidence Scotland Yard needs. If only the beguiling Miss Bertram wasn’t so damn distracting…
As an unexpected but undeniable passion flares between Lucy and Will, confidences are exchanged and dark secrets come to light. But will a murderer, determined to stay hidden, destroy their chances of finding a happy-ever-after?