Using $pp$ collision data corresponding to an integrated luminosity of $5.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the LHCb detector at a center-of-mass energy of 13 TeV, the ${B}^{0}\ensuremath{\rightarrow}{D}^{\ensuremath{-}}{D}^{+}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decay is studied. A new excited ${D}_{s}^{+}$ meson is observed decaying into the ${D}^{+}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ final state with large statistical significance. The pole mass and width, and the spin parity of the new state are measured with an amplitude analysis to be ${m}_{R}=2591\ifmmode\pm\else\textpm\fi{}6\ifmmode\pm\else\textpm\fi{}7\text{ }\text{ }\mathrm{MeV}$, ${\mathrm{\ensuremath{\Gamma}}}_{R}=89\ifmmode\pm\else\textpm\fi{}16\ifmmode\pm\else\textpm\fi{}12\text{ }\text{ }\mathrm{MeV}$, and ${J}^{P}={0}^{\ensuremath{-}}$, where the first uncertainty is statistical and the second systematic. Fit fractions for all components in the amplitude analysis are also reported. The new resonance, denoted as ${D}_{s0}(2590{)}^{+}$, is a strong candidate to be the ${D}_{s}(2{^{1}S}_{0}{)}^{+}$ state, the radial excitation of the pseudoscalar ground-state ${D}_{s}^{+}$ meson.