The Transformation of Philip Jettan is set in England and France in the 1750s. The titular Philip Jettan is an unpolished young country gentleman in love with Cleone. Cleone is also in love with him, but wishes he were more sophisticated. Due to poor communication and insecurity on both their parts, she rejects him, and he sets off to attempt to transform himself into the fashionable gentleman she desires.

Transformation is an example of an early romance novel. It was the only novel Heyer published under a pseudonym (as “Stella Martin”), and, according to one source, it was written in just three weeks. In 1930 it was republished as Powder and Patch, but without the last chapter.