The main theme could be about the struggle for freedom or the fight against oppression. Since many novels with such titles often deal with characters facing difficult circumstances and striving for a better life.
The main theme of 'Iqbal novel book' is likely the power of hope and resistance. In the story, the characters face difficult situations, yet they keep their hope alive and resist the unjust circumstances. They don't give in to the hardships and keep fighting for a better future. This theme is shown through the various trials and tribulations that the characters go through and how they emerge stronger in the end.
Since I have no prior knowledge of the Rajan Iqbal series novel, it's impossible to accurately state the main themes. But in general, novels can explore themes such as cultural identity, social justice, and the human condition. To find out the main themes of this series, you could read reviews, or if possible, read the books in the series and analyze them yourself.