Forty of India's biggest energy companies are being investigated by a wing of the Union Ministry of Finance for over-invoicing of imported coal. The artificially higher prices of coal have been passed on to electricity consumers across the country. The scam is conservatively estimated by government officials at no less than ₹29,000 crore, a third of which is in the form of higher power tariffs. Big names from the corporate sector, notably the Adani Group and Anil Dhirubhai Ambani Group, are being probed for their alleged involvement in the scandal. An exclusive report.