| Lay On, Mac Duff! | |
| Author: | Charlotte Armstrong |
| Country: | United States |
| Language: | English |
| Series: | MacDougal Duff |
| Genre: | Mystery |
| Publisher: | Coward-McCann |
| Release Date: | 1942 |
| Media Type: | |
| Followed By: | The Case of the Weird Sisters |
Lay On, Mac Duff! is a 1942 mystery novel by the American writer Charlotte Armstrong. It was first published in New York by Coward-McCann, an imprint of Putnam.[1] The first of a trilogy featuring amateur detective MacDougal Duff, it was followed by The Case of the Weird Sisters (1943) and The Innocent Flower (1945). The title is a punning reference to both the protagonist's name and a line from William Shakespeare's Macbeth, with the following two titles in the trilogy also referring to the play.[2] It was Armstrong's debut novel, following two Broadway plays that made no great impact.