On the hunt for the lost city of Z

(CNN)When David Grann lost his guide deep in the Brazilian Amazon, fear took hold.

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Fawcett pictured in 1911 on his fourth expedition.

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Fawcett mapping the border between Bolivia and Brazil in 1908.

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Charlie Hunnam as Lt. Col. Percy Fawcett in “The Lost City of Z.”

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Fawcett was considered radical in his day for taking a diplomatic approach with Amazonian tribes.

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Archaeologist Michael Heckenberger and Kuikuro chief Afukaka.

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Jack Fawcett on 1925’s fateful expedition.

“The Lost City of Z” opens in UK theaters March 24 and in the US April 21. David Grann’s latest book “Killers of the Flower Moon” hits bookshops April 20.