We present a search and analysis of variable stars in the recently discovered Crater II dwarf galaxy .
Based on B , V , I data collected with the Isaac Newton Telescope ( FoV \sim 0.44 square degrees ) we detected 37 variable stars , of which 34 are bone-fide RR Lyrae stars of Crater II ( 28 RRab , 4 RRc , 2 RRd ) .
We applied the metal-independent ( V , B - V ) Period–Wesenheit relation and derived a true distance modulus ( \mu = 20.30 \pm 0.08 mag ( \sigma =0.16 mag ) .
Individual metallicities for RR Lyrae stars were derived by inversion of the predicted I -band Period-Luminosity relation .
We find a mean metallicity of [ Fe/H ] =-1.64 and a standard deviation of \sigma _ { [ Fe / H ] } =0.21 dex , compatible with either negligible or vanishing intrinsic metallicity dispersion .
The analysis of the Colour-Magnitude Diagram reveals a stark paucity of blue horizontal branch stars , at odds with other Galactic dwarfs , and globular clusters with similar metal abundances .