In the depths of winter, Shenanigan Swift and her family are summoned to America, where Daisy's brother, Dandelion DeMille, is in danger.

Racing to DeMille family home - a 72-storey greenhouse in the heart of New York City - Shenanigan is too late to stop a murder. But it's Dandelion's Uncle Charlie who has fallen victim to a mystery assassin.

As a snowstorm rages outside, Shenanigan, Felicity, Phenomena and Erf must uncover both motive and means. But when every room is packed with poisonous plants and deadly creatures, how will they ever uncover what really happened in The Greenhouse?