Massachusetts legalized the sale of recreational marijuana with the ambition to be different - and better. Its law was the first in the nation to promote social justice goals, including ways to promote small and minority entrepreneurs. Other parts of the law made it clear: Big national companies weren't supposed to monopolize here.

But two years since the law went into effect, troubling signs loom. This three-part series, "Hidden Titans of Pot," uncovers stealth moves by large investors poised to dominate this nascent industry and outmaneuver regulators.

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