Amanda Quick - The Ladies of Lantern Street (#1-2)

Crystal Gardens
Evangeline Ames has rented a country cottage far from the London streets where she was recently attacked. Fascinated by the paranormal energy of nearby Crystal Gardens, she finds pleasure in sneaking past the wall to explore the grounds. And when her life is threatened again, she instinctively goes to the gardens for safety.
Lucas Sebastian has never been one to ignore a lady in danger, even if she is trespassing on his property. Quickly disposing of her would-be assassin, he insists they keep the matter private. There are rumours enough already, about treasure buried under his garden, and occult botanical experiments performed by his uncle – who died of mysterious causes.
With Evangeline's skill for detection, and Lucas's sense of the criminal mind, they soon discover that they have a common enemy. And as the energy emanating from Crystal Gardens intensifies, they realize that to survive they must unearth what has been buried for too long...

The Mystery Woman
Beatrice Lockwood, one of the intrepid ladies of Lantern Street, is in the middle of a case when her past comes back to haunt her. Joshua North, a former spy for the Crown, has come out of a self-imposed retirement after a disastrous case that left him scarred and forced to use a cane. He is hunting the villain who is blackmailing his sister.

The trail leads him to Beatrice who is his chief suspect. But when he realizes that she is not the blackmailer they set out to find the real extortionist. Passion flares between them as they dodge a professional assassin. Meanwhile a mysterious scientist intent on resurrecting his dead lover using an ancient Egyptian formula for preserving the bodies of the dead is also hunting Beatrice. He is keeping his dead love perfectly preserved in a special, crystal-topped sarcophagus filled with the special fluid. But he needs Beatrice's paranormal talent to activate the reviving properties of the preservative in the coffin. Time is running out for everyone involved.

The two cases collide at a mysterious country-house filled with artifacts from ancient Egyptian tombs. The drama concludes in the mad scientist's laboratory where Joshua discovers that the past he thought was dead is still very much alive - sort of.