Under section 34 the essence of liability is to be found in the existence of a common intention animating the accused leading to the doing of a criminal act in furtherance of such intention. 

It is difficult if not impossible, to procure direct evidence to prove the intention of an individual; in most cases it has to be inferred from his act etc.  Such an inference should never be reached unless it is necessary inference deducible from the circumstances of the case. 

Common intention within in the meaning of section 34 implies a prearranged plan, and to convict the accused of an offence applying this section, it should be proved that the criminal act was done in concert pursuant to the prearranged plan.