Construction workers are painting over the Boko Haram graffiti. Plywood frames are rising in the place of homes destroyed by grenades and bombs. Thousands of refugees are returning. On the surface, this city once occupied by Islamist extremists is slowly returning to normal.

Except for one horrifying fact: Hundreds of children are missing.

Most of them were seized by Boko Haram in the fall of 2014. Months earlier, in April, the militants had carried off 276 schoolgirls from the town of Chibok, a kidnapping that became the subject of a global campaign known by the hashtag #BringBackOurGirls. But there has been little attention to the lost children of Damasak. Residents say they total more than 500. All but a handful are still unaccounted for.

In the ruins of the city, everyone seems to be missing a son or a daughter, a brother or a sister. Outside the mud walls of his roofless house, Aji Bakar holds a picture of his chubby-cheeked 9-year-old grandson, who was kidnapped from his classroom in September 2014.