Block on the Hill

Mirante Museum, a collector's mansion high in Santa Teresa, Rio de Janeiro. Carnival Friday, 4 p.m. The Bloco das Corujas street party was coming down the hill outside the gate, with a thousand revelers and a full drum band.

In the middle of the party, four masked bate-bolasbate-bola Carnival costume from Rio's suburbs: a loose, colorful outfit with a mask, often carrying a ball on a stick. walked into the museum, held up the guards and six visitors, and took the four most valuable paintings in the collection off the wall. Half an hour later they left with the party and turned into four more costumes in the crowd.

The cameras recorded nothing. The paintings, which should have been fixed with steel locks, came loose with one snip of pliers. The thieves looked at no other work: they knew exactly where to go.

Someone on the inside drew them the way. Three people knew this museum that afternoon, and one of them opened the door without touching the lock.

The mansion's gallery, with four pale rectangles on the wall and cut nylon wires on the hooks.