From Rocklopedia Fakebandica
Swing Sisson has a deal to premiere his songs at New York's smart Clover Club. Nazi fifth columnists plot to murder Gershwin to hurt American morale. They sneak into his mansion to rig his piano with a gun that will shoot when a note is played. But Gershwin and Sisson and pals come back early and surprise the goons, leading to a fist fight.
His name is a portmanteau of real songwriters Irving Berlin and George Gershwin.