This book is number 4 in the “No. 1 Ladies’ Detective Agency” series. However, I think you’d be able to appreciate and enjoy this book without reading the others. I think I’ve only read a couple of them. 

There is a rival detective agency in town, Mma Makutsi opens up a typing school for men and Mma Ramotswe helps a wealthy man redeem his past. 
This is a lovely, light, quite whimsical story told in the warm, evocative tone the series is renowned for. The country of Botswana is just as much a character in the novel as the people, and you really feel transported there. 

A light, easy read with elements of humour and intrigue.