Short answers, pulled from the story.
The Indian Rebellion of 1857 began on the 10th of May 1857 as a mutiny of sepoys at the British East India Company's garrison in Meerut, a town 40 miles northeast of Delhi. It then spread into other mutinies and civilian rebellions across the upper Gangetic plain and central India.
The rebellion resulted from an accumulation of causes including resentment over invasive social reforms, harsh land taxes, the annexation of princely states under the Doctrine of Lapse, changes to soldiers' pay and service conditions, and fears that the company was encouraging mass conversions to Christianity. The immediate flashpoint was the introduction of the Pattern 1853 Enfield rifle, whose cartridges were rumoured to be greased with cow tallow and pig lard, violating Hindu and Muslim religious practice.
Mangal Pandey was a 29-year-old soldier of the 34th Bengal Native Infantry who, on the 29th of March 1857 at the Barrackpore parade ground near Calcutta, declared he would rebel against his commanders and opened fire on his superiors. He was court-martialled on the 6th of April 1857 and hanged two days later. His punishment and the formal disbanding of his regiment helped foment the wider rebellion.
Bahadur Shah II, the 81-year-old Mughal ruler, was declared Emperor of Hindustan by rebel sepoys who reached Delhi on the 11th of May 1857. Most accounts suggest he was coerced into accepting their allegiance. After the British retook Delhi in September 1857, Zafar fled to Humayun's tomb and was arrested. The day after his capture, British Major William Hodson had Zafar's sons Mirza Mughal and Mirza Khizr Sultan and grandson Mirza Abu Bakr shot at the Khooni Darwaza near Delhi Gate.
Around 206 women and children, along with five men, were held in a building called the Bibighar in Cawnpore after surviving an initial river massacre on the 27th of June 1857. When a British relief force approached in mid-July, rebel leaders ordered the hostages killed. After sepoys refused the order, five individuals carried out the killings with knives and hatchets. The bodies were thrown into a well 50 feet deep and the remainder into the Ganges.
The rebellion was militarily contained with the rebels' defeat at Gwalior on the 20th of June 1858, though Britain did not declare hostilities formally ended until the 8th of July 1859. The consequences were transformative: the East India Company was dissolved, Britain assumed direct rule through the Government of India Act 1858, and the British Raj was established. On the 1st of November 1858, Queen Victoria issued a proclamation promising Indians rights comparable to other British subjects, a text Indians would invoke in the decades of growing nationalist sentiment that followed.