CAIRO — My last text exchange with the Egyptian activist and software programmer Alaa Abd El Fattah was Saturday morning, less than 24 hours before he was kidnapped by government security agents. We shared messages about our personal relationships and made a plan to spend Monday together. I imagined that he would come over for breakfast; then we might go to the pool at our local sports club. It was there that we had last spent the afternoon together a couple of weeks ago, along with his son and my goddaughter.

That day, over an extended breakfast that began on my terrace, we had discussed the writers Olga Tokarczuk and W.G. Sebald (shared favorites); the animal he most likes, the narwhal; and the writing projects we were each working on. Later in the pool, he had challenged the children to back-flips and underwater races.

Alaa was six months out of prison then, having completed a five-year sentence on charges of protesting in defiance of an anti-protest law. Yet he wasn’t fully free. Subjected to daily probation for the next five years, Alaa had to check in to his local police station each evening at 6 p.m. and stay overnight until 6 a.m. There, during the hours he was awake, he mostly wrote, longhand, and read fiction. As dawn approached, he would pack up his bedding and the gear he took to make his police-station cubicle habitable and head home to shower before trying to make the most of his 12-hour day. It was just before his dawn began on Sunday that state security agents took him away on the sly from his police cell — essentially, kidnapped him — and transferred him to a maximum-security prison. His mother, the university professor and rights defender Laila Soueif, had come to the station to pick him up and was told he had already left. When she saw that the street was in lockdown, she knew something was up.

Alaa has been arrested under four governments, which makes his new detention as unsurprising as it is hard to believe. The government seems to view him as something of a galvanizing figure and appears to fear his possible influence on what looks, just now, like a burgeoning opposition. Over the past few weeks, Mohammed Ali, an Egyptian building contractor who took jobs from the armed forces for 15 years, has posted numerous videos from exile in Spain detailing the excesses of President Abdel Fattah el-Sisi’s spending on personal homes, palaces and projects of little apparent benefit to the country. The videos, in which Mr. Ali chain-smokes, speaks in local ghetto-slang and juxtaposes details of government spending with Mr. el-Sisi’s reminder to Egyptians that “we are poor,” hit a chord. With millions of viewings, the videos spurred small, spontaneous protests on Sept. 20 and again last Friday, leading to the security crackdown that Alaa was swept up in. Nearly 2,200 people have been arrested since those first protests, according to the Egyptian Center for Economic and Social Rights, and vast numbers of police and special forces have been sent out to patrol the streets.