Let $A$ be a closed polar subset of a domain $D$ in $ℂ$. We give a complete description of the pluripolar hull ${\Gamma }_{D\times ℂ}^{*}$ of the graph $\Gamma$ of a holomorphic function defined on $D\setminus A$. To achieve this, we prove for pluriharmonic measure certain semi-continuity properties and a localization principle.