Mystery: The Constant Gardner: by John le Carré

The beautiful Tessa Quayle is murdered near Lake Turkana in northern Kenya, the birthplace of mankind. And her putative African lover and travelling companion has vanished from the scene of the crime. Tessa’s husband, a career diplomat and amateur gardener at the British High Commission in Nairobi, sets out on a personal odyssey in pursuit of the killers and their motive. On his way he meets terror, violence, and conspiracy, but his greatest discovery is the woman he barely had time to love.