Sharpe's Tiger: The Siege of Seringapatam, 1799 (The Sharpe Series, Book 1) by Bernard Cornwell
When a senior British officer is captured by the Tippoo of Mysore's forces, Sharpe is offered a chance to attempt a rescue, which in turn offers an escape from the tyrannical Sergeant Obadiah Hakeswill.
But in fleeing Hakeswill, Sharpe enters the exotic and dangerous world of the Tippoo. An adventure that will require all of his wits just to stay alive, let alone save the British army from catastrophe.
Soldier, hero, rogue - Sharpe is the man you always want on your side. Born in poverty, he joined the army to escape jail and climbed the ranks by sheer brutal courage. He knows no other family than the regiment of the 95th Rifles whose green jacket he proudly wears.