The Religious Body by Catherine Aird

Inspector C.D. Sloan of the Calleshire C.I.D. makes his first appearance here as he looks into the murder of a nun at the Convent of St. Anselm.

Apparently Sister Anne tumbled down the stairs to the basement to her death. Accidental? Upon closer examination, that didn't explain the evidence of a vicious blow to the back of her head. When Sloan delves into her background, the motives for murder multiply.

First published in 1966, "The Religious Body" was Aird's first book and immediately established her as one of the leading exponents of the post-WW2 English traditional mystery.