If by "The Beginning" you meant the chronological beginning of the entire Spartacus story, that is Gods of the Arena (2011):
A dystopian 2012 or a parallel universe where historical events like the Spartacus revolt are replayed in a modern context. Spartacus MMXII- The Beginning -2012-
...track down this relic. It isn't a masterpiece of storytelling, but it is a masterpiece of . If by "The Beginning" you meant the chronological