They Watched by Night is a 1941 detective novel by John Rhode, the pen name of the British writer Cecil Street.

[1][2] It is the thirty fifth in his long-running series of novels featuring Lancelot Priestley, a Golden Age armchair detective.

[3] It was published in the United States by Dodd Mead with the alternative title Signal for Death.

You can help Wikipedia by expanding it.See guidelines for writing about novels.

Further suggestions might be found on the article's talk page.