The crystal structure of a high-pressure phase of silane $(\mathrm{Si}{\mathrm{H}}_{4})$, observed between 10 and $25\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, is solved using powder synchrotron x-ray diffraction and shown to be of the $\mathrm{Sn}{\mathrm{Br}}_{4}$ type. The phase is an insulating molecular solid with a monoclinic unit cell containing four tetrahedrally bonded molecules, space group $P{2}_{1}∕c$. Ab initio calculations show the $\mathrm{Sn}{\mathrm{Br}}_{4}$-type structure to be favored in this pressure range relative to other recently proposed structures. The fit of the pressure dependence of volume to the Birch-Murnagham equation of state gives the following parameters at ambient pressure if ${K}_{0}^{\ensuremath{'}}$ is fixed to 4: ${V}_{0}=250(9)\phantom{\rule{0.3em}{0ex}}{\AA{}}^{3}$ and ${K}_{0}=7.8(9)\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ for the experimental data, and ${V}_{0}=255(2)\phantom{\rule{0.3em}{0ex}}{\AA{}}^{3}$ and ${K}_{0}=6.1(2)\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ for the data obtained from ab initio calculations.