  We study the chiral de Rham complex (CDR) over a manifold $M$ with holonomy
$\rm G_2$. We prove that the vertex algebra of global sections of the CDR
associated to $M$ contains two commuting copies of the Shatashvili-Vafa $\rm
G_2$ superconformal algebra. Our proof is a tour de force, based on explicit
computations.
