The crux of One Night @ the Call Center by Chetan Bhagat is about six young professionals working the night shift in a call center in Gurgaon, India, who face personal and professional struggles and are forced to confront their challenges during a pivotal night.

Key Themes:

1. Personal and Career Struggles:
   The characters are dealing with dissatisfaction in their personal lives and careers, trying to balance societal expectations, family pressures, and their own aspirations. They are at crossroads, questioning their choices and the future.

2. Cultural Clash:
   The story contrasts the traditional Indian values of the characters with the modern, Westernized influence from their work in a call center. This clash creates internal conflicts as they navigate their personal identities and desires.

3. Love and Relationships:
   Romantic relationships, especially between Shyam and Priyanka, and friendships are central to the narrative, reflecting how personal connections are shaped by the pressures of work and society.

4. Self-Discovery and Motivation:
   Through a mysterious phone call from a man claiming to be God, the characters are pushed to reflect on their lives, leading them to make important decisions about what they truly want and how they can achieve fulfillment.

Core Message:

The novel conveys the importance of self-reflection, taking control of one's destiny, and overcoming personal and professional obstacles. It encourages the characters to make bold decisions and seek happiness, while also highlighting the struggles of balancing career pressures with the pursuit of personal dreams. Ultimately, the book underscores that life is shaped by the choices we make, and it is never too late to change direction.