alternate term: English drawing-room mystery
This type of mystery characteristically involves a group of people brought together, usually in a large house, for a specific purpose. When one member of the group turns up dead, all the others immediately are suspects and become suspicious of each other. The detective, frequently an amateur sleuth, deduces the murderer’s identity through shrewd observation of the participants. The story often ends with all participants gathered in the drawing room; the sleuth examines in turn each one’s motives for the murder, saving the guilty party for last.
In a cozy, the unpleasant business of the murder usually occurs “off stage.” Someone discovers a corpse, but readers are spared the details of how the killing and death occur.
“This term describes the underlying attitude behind a certain type of mystery story. Although it is frequently treated as the opposite of hard-boiled, that impression is inaccurate. The proper antonym of cozy is noir. A cozy supposes a benign universe: These murders we have before us are unsettling, but once we figure out who the killer is, we can get back to living our decent and pleasant lives” (Source: DeAndrea, 401).