  A first study of CP violation in the decay modes $B^\pm\to [K^0_{\rm S} K^\pm
\pi^\mp]_D h^\pm$ and $B^\pm\to [K^0_{\rm S} K^\mp \pi^\pm]_D h^\pm$, where $h$
labels a $K$ or $\pi$ meson and $D$ labels a $D^0$ or $\overline{D}^0$ meson,
is performed. The analysis uses the LHCb data set collected in $pp$ collisions,
corresponding to an integrated luminosity of 3 fb$^{-1}$. The analysis is
sensitive to the CP-violating CKM phase $\gamma$ through seven observables: one
charge asymmetry in each of the four modes and three ratios of the
charge-integrated yields. The results are consistent with measurements of
$\gamma$ using other decay modes.
