‘A’ is carried off by a tiger. ‘Z’ fires at the tiger in good faith intending to rescue ‘A’, knowing it to be likely that the shot may kill ‘A’. The shot fired by ‘Z’ gives ‘A’ a mortal wound. ‘Z’ has committed

This is a classic case of the doctrine of necessity (Section 81 IPC). Z acted in good faith to rescue A from a tiger, even knowing the risk to A's life. When an act is done by lawful means, with good faith and no criminal intent, to prevent harm, it amounts to no offence. The law recognizes that sometimes a person must cause minor harm to prevent greater harm.