When Occupy Central With Love and Peace, a citizens’ movement for the popular election of Hong Kong’s leader, erupted in late 2014, Jason Y. Ng, a lawyer and writer, was in the middle of the tumult. His new book, “Umbrellas in Bloom,” offers a vivid account of the street protests that paralyzed parts of Hong Kong for 79 days.

With firsthand observations, timelines, charts and explanations of the semiautonomous Chinese territory’s arcane political system — an uneasy blend of the relics of undemocratic British colonial rule and new elements of undemocratic Chinese rule — Mr. Ng spells out what many Hong Kong people, particularly younger ones, are chafing against. In an interview, he reflected on the Occupy movement, also called the Umbrella Revolution, and what happens next.

Q. What did the Occupy movement achieve?

A. Because of Occupy, politics is now on everyone’s mind and lips, and social justice has replaced social status on our priority list. It has also engendered the so-called Umbrella generation: youth who now spend their time debating and scrutinizing every government policy on social media. Some of them are even running for public office.

But the picture is not all rosy. Social awakening notwithstanding, Occupy ultimately failed to gain any concessions from Beijing on the issue of universal suffrage. That left many Hong Kongers disillusioned and bitter. Society is more polarized than ever, anti-mainland sentiment is at an all-time high and the rise of localism is radicalizing the opposition. We are bracing for more turbulence ahead.