Crime Fiction: female serial killer, killing without a real motive

[CapitalC]

Hey guys,

 

I became interested in the idea of a female 'recreational' killer (not killing for revenge or killing specific individuals) when I saw a book like this adverstied as a poster in bookshops/supermarkets in London about 3 years ago. I forgot the name of the book and havent been able to find it since.

 

There are a fair few crime books where the serial killer is a man who kills for no other reason than the enjoyment of killing, but I have not come across a book where the killer is female.

 

Any ideas/ suggestions?