The story revolves around the trials and tribulations of a young Polish priest, Father Stephan Kovalski (a French priest named Paul Lambert in the original French version), the hardships endured by a rickshaw puller, Hasari Pal in Calcutta (Kolkata), India, and in the second half of the book, also the experiences of a young American doctor, Max Loeb.

In the journey of Kovalski's acceptance as the Big Brother for the slum dwellers, he encounters moments of everyday miracles in the midst of appalling poverty and ignorance.

The third main character is a rich American doctor, who has just finished medical school and wants to do something with purpose before opening up his practice catering to the wealthy.

The book received the Christopher Award[3] in 1986, given for creative work that exhibits the highest values of the human spirit.

The book is set in the slum of Anand Nagar, which is based on the area of Pilkhana in Howrah, West Bengal, India.