The way Agnes Chow describes it, Hong Kong’s national security police offered her a deal. Renounce her activist past, and she could leave Hong Kong for Canada to study. Reject the offer, and she would remain confined to the city. She took the deal.

The 27-year-old former protest leader last week provided a rare view of the methods used by Hong Kong’s secretive police wing when she detailed in an Instagram post everything she did to get her passport back.