Dye Hard. Australian Amateur Sleuth, #3

Obnoxious ghost hunters descend on Cressida Upthorpe's boarding house, convinced it must be a source of paranormal activity given that three murders have occurred there in a short space of time. After one of the ghost hunters is murdered with poisoned hair dye, Sibyl does her best to keep well away from the investigation, that is, until Cressida almost falls victim. With the bumbling detectives back in town and on the scene, Sibyl races to comb through the suspects before the body count rises.
It's all in a dye's work. Dye Hard is Book 3 in the USA Today Bestselling cozy mystery series, Australian Amateur Sleuth.