A freak accident enables a tropical aquarium species of glass anemone, Aiptasia, to develop an outer protective skin enabling it to move out of the water onto land. By stinging, stunning and capturing its victims it is able to find a new food supply readily available in the streets of London. Beware where you walk, especially at night, as lurking in the corner or above you may be Aiptasia. If you feel something touching your legs or body, flee straight away before the tentacles drag you into the oral cavity to be digested. Check yourselves, your homes, your possessions and your animals as it only needs a few cells from the parent as big as a full stop to start to establish and become a three metre giant.