Caryl Churchill 
The Skriker (NHB Modern Plays) [EPUB ebook] 

An extraordinary play combining English folk tales with modern urban life in a physically and verbally stunning creation.
The Skriker of English legend is 'a shapeshifter and death portent, ancient and damaged'. In the play we follow in its search for love and revenge, as it pursues two young women to London, changing its shape at every new encounter. Along with the Skriker come Rawheadandbloodybones, the Kelpie, the Green Lady, Black Dog and more, till the whole country is swarming with enticing and angry creatures that have burst from the underworld.
'unwholesome, hypnotic and born in the dark… spellbinding' — Independent on Sunday