If you can get over the premise that the well brought up heroine (in Regency England) devotes her secret life to ensuring that merchants give full measure (before standardised weights and measures were brought in by law), then this is a fun light read. Cole (Duke of Colehaven) makes a bet that he can get a friend's wallflower sister married off before the end of the season, however Diana Middleton has no intention of marrying and losing her freedom to run around London in disguise, threatening to 'shop' shopkeepers who don't deal fairly with their customers. While she may not like the idea of getting shackled in marriage, she is open to the idea of a little seduction, especially since the Duke of Colehaven seems to be intent on turning up and spoiling her wallflower act. Cole begins to despair of ever winning his bet since he's suddenly realised he doesn't want to see Miss Middleton married off to anyone else but him. It's a short and sweet novel with the expected ending, but still worth reading.