Footprints in the Snow

On a cold December evening two boys are found face-down in the snow, dead with only a small trail of rapidly disappearing footprints in the snow around them as evidence. The case goes cold and twenty years later DI Miles Kjeller and his team pick it up after two more boys turn up dead with the same MO, face down in December snow. Is it the same person? A copy-cat? Or completely unrelated?
That is up to Miles and his team to find out.