We study the transverse spin-dependent nucleon structure function ${g}_{2}(x, {Q}^{2})$ in leading order at large ${Q}^{2}$. After reviewing the operator-product-expansion analysis of ${g}_{2}(x, {Q}^{2})$ we calculate the twist-3 contributions which arise from quark-gluon interactions and quark masses in the bag model. The result confirms the presence of significant twist-3 effects in ${g}_{2}(x, {Q}^{2})$. We discuss two questions raised by our analysis: the validity of the Burkhardt-Cottingham sum rule and the relation to previous calculations of ${g}_{2}(x, {Q}^{2})$ in versions of the parton model.