BEIRUT — One evening in the early days of Syria’s uprising, Mohsen al-Masri’s band of activists slipped through the Damascus streets and waited for the coast to clear. Then they crouched, opened their bags and let out a stream of color.

Thousands of ping-pong balls, painted green, pink, blue and yellow, bounced past policemen, who scrambled to stop them. Residents would find balls tucked in nooks and crannies for months. Each was marked with a single word: “Freedom.”

The punishment for Masri’s acts of peaceful protest would begin a journey into hell, unusual not because of what he saw, but because he survived.

In a series of interviews, he described how he was tortured and interrogated over a two-year period in four detention facilities before arriving in a hospital at the heart of a nationwide system of brutality.

The hospital, known as 601, is not the only site of torture in Syria. But after it was seen in a cache of photographs showing thousands of skeletal corpses, it became one of the most notorious.
Mohsen al-Masri before and after his imprisonment. (Mohsen al-Masri /Mohsen al-Masri )