Miss Merula Merriweather is not like other women her age: instead of hunting for a husband at balls and soirees she spends her time in a conservatory hatching exotic creatures. As the Royal Zoological Society won't accept a woman's accomplishments, she has her uncle Rupert take credit for her achievements. But at a zoological lecture, the guest of honor dies after contact with one of Merula's butterflies, and Merula's uncle is arrested for murder. In an attempt to safeguard evidence to prove his innocence, Merula almost gets killed but for the timely interference of enigmatic Lord Raven Royston. Viewing natural history as a last resort to regain respectability lost by too many dubious business investments, Raven didn't expect his first lecture to take a murderous turn. Feeling partially responsible because he encouraged Merula to release the gigantic butterfly from the glass case in which it was kept, Raven suggests they solve the puzzle of Lady Sophia's sudden death together by looking closer at her relations with estranged friends, long suffering staff and the man groomed to be her heir, so close to her money and yet unable to touch any of it.