Firstly, the fact that James has made the detective female is a significant subversion, it conveys the changing times in which it was written, 1982. During this time, roles of women and their social roles and barriers were changing rapidly, and this is reflective in the novel. As well as challenging the role of women in society another obvious challenge to the genre of crime writing is the denouement is not performed at the end of the novel, as is usually the case for many traditional 'cosy' novels, but is instead closer to the middle crisis and unravelling of the case. Cordelia does not perform the resolution herself and no other guests are present during its unfolding. Instead, Ambrose undertakes the denoument, much to the embarrassment and fallibility of Cordelia.
Other slight subversions of the genre include the fact that Cordelia Gray has an uneasy past and she lacks the intellectual capacity of the traditional cosy detective and the isolated setting at Sir Ambrose Gorringe's Victorian castle is a convention of the cosy but the blending of the cosy with the gothic genre challenges the norm for crime writing.
On the other hand occasionally a convention was seen to be adhered too which is often hard to avoid. In the Skull beneath the Skin Society is left unstable, as Ambrose was never put behind bars. The killings weren’t really justified by the characters, or justified in a way we could understand as normal people. This convention holds true to Contemporary Crime Fiction.