"Daddy, there's a man in our room..." What a chilling start to this Gothic horror debut novel by William Friend. The story of widowed Alfie and his twin daughters, there is some great atmospheric writing here as the girls' imaginary friend turns into something much more creepy. The novel encompasses themes of grief and loss, faith and obsession, and the bond between twins. I really enjoyed the first half of the book, the tension mounts as you start to question whether Black Mamba is just a juvenile fantasy dreamed up by grieving children or a manifestation of something sinister. Unfortunately as the story went on I felt it flagged quite a bit. The back story involving the grandparents and their religious beliefs was not fully explained, and I found the ending disappointing, small revelations rather than a satisfying climax, it had too many loose ends and an ambiguous twist.