Kat Richardson is an American author best known for her Greywalker urban fantasy series. The series consists of nine novels. In the 9th novel she states, "This is the last Greywalker novel, at least for a while." Harper Blaine, the heroine of the series, is a private investigator living in Seattle and was killed whilst pursuing a case. She was dead for only two minutes and brought back by medical intervention. During her recovery, she discovers she is able to recognize witches and vampires, see ghosts and is aware of other elements of the supernatural world. She discovers that her brief death has turned her into a Greywalker, a human able to move back and forth at will through the Grey, the realm that exists between our world and the next.