Sara's father wrote to her often, and Sara wrote loving little letters back to him. One day a very exciting letter arrived. Everybody in the school talked about it for days. 'My friend,' wrote Mr Crewe, 'has some mines in northern India, and a month ago his workers found diamonds there. There are thousands of diamonds in these mines, but it is expensive work to get them out. My friend needs my help. So, Little Missus' (this was Mr Crewe's special name for Sara), 'I am putting all my money into my friend's diamond mines, and one day you and I are going to be very rich ...'