We propose to search for CP violation through the twofold angular distributions in the four-body decays of bottom and charmed hadrons. The two polar angles in the twofold angular distributions are correlated, to which the interferences of intermediate resonances are one important origin. These interferences will leave tracks in the twofold angular distributions, with which the CP violation can be studied. Special attention is paid to the case when all the intermediate resonances are different, which is unique to four-body decays. It is suggested to look for CP violation in four-body decays suc...
