Theory:

The story "Expert Detectives" is an extract from Sharada Dwivedi's novel, "The Broken Flute".  "The Broken Flute" is a children's novel published in the year \(1994\) . The novel is named after Nishad's (one of the major characters of the novel) interest in the instrument.
 
Some of the characters featured in the extract are:
  1. Maya: the narrator
  2. Nishad (a.k.a Seven): the narrator's younger brother
  3. Mr Nath: a central character on which the story is built
  4. Ramesh
  5. Mr Nath's visitor
  6. Maya's and Nishad's mother: a doctor
  7. People in Shankar House
  8. Mr Mehta
Being the narrator, Maya often refers to Nishad through the nickname she had given him- "Seven". Nishad was named after a scale in the Indian Music- Shadaj, Rishabh, Gandhar, Madhyam, Pancham, Dhaivat, and Nishad - famously known as Sa - Re - Ga - Ma - Pa - Da - Ni. Since his name is the seventh note in the swaras, Maya calls him Seven.
 
The lesson explores the imaginative, inquisitive, and creative minds of children. Moreover, the lesson is constructed on the relationship and the interactions between the siblings.