[12] The film depicts the journey of lawyer Raphael Lemkin and his efforts in lobbying the United Nations to establish the Genocide Convention.

The movie also focuses on four people inspired by Lemkin: Samantha Power, United States Ambassador to the United Nations; Benjamin B. Ferencz, Chief Prosecutor in the Einsatzgruppen trial at Nuremberg; Luis Moreno Ocampo, first Prosecutor of the International Criminal Court; and Emmanuel Uwurukundo, head of operations for refugee camps in Chad set up by the United Nations High Commissioner for Refugees in the War in Darfur.

Dennis Harvey, in his review for Variety, wrote that "Edet Belzberg's sweeping survey of global genocide is an impressive and artful cinematic thesis of palpable substance.

"[15] Duane Byrge of The Hollywood Reporter gave the film positive review and said that "An exhaustive, complex look at genocide with a sobering and historically predictable prognosis.

"[16] Steve Greene from Indiewire, in his review, wrote that "As a documentary, "Watchers of the Sky” shows how even capturing that progress is a monumental task in itself.