Strings on ${\text{AdS}}_3\times {\text{S}}^3\times {\text{S}}^3\times {\text{S}}^1$

String theory on ${\rm AdS}_3 \times {\rm S}^3 \times {\rm S}^3 \times {\rm S}^1$withpureNS-NSfluxandminimalfluxthroughoneofthetwo${\rm S}^3$'s is studied from a world-sheet perspective. It is shown that the spacetime spectrum, as well as the algebra of spectrum generating operators, matches precisely that of the symmetric orbifold of ${\rm S}^3\times $\mathrm{S}$^1$inthelarge$N$ limit. This gives strong support for the proposal that these two descriptions are exactly dual to one another.