Outside Athens, Korydallos Prison holds 2,000 of the country's most dangerous prisoners, but not the country's most wanted man, Nikos Palaiokostas.
He's been on the run for 16 years since a jailbreak in 1990.
This weekend, Palaiokostas returned to Korydallos to spring his brother and fly him to freedom. The plot was audacious, yet simple. Prison walls are high, but the exercise yard is open to the sky.
Palaiokostas and an accomplice chartered a helicopter for a sightseeing ride. Once airborne, they threatened the pilot with a hand grenade and forced him to fly low under the radar and land in the crowded recreation yard of the high security prison.
As Palaiokostas threw smoke grenades, his brother Vassilis and another inmate jumped aboard. The pilot then flew the men to a nearby field. By the time police arrived on the scene, the men had escaped on motorcycles. All police found was a shaken pilot and a grenade.
Prison guards say they initially thought the helicopter was flown by ministry officials on a surprise inspection, so they did nothing. By the time the chopper was airborne again, it was too late.
"We cannot shoot down a helicopter flying over busy streets and houses," one guard said.
The motorcycles the men used to escape were later found abandoned. Vassilis was serving a 25-year term for bank robbery and the kidnapping of a Greek businessman. Nikos had originally been imprisoned for his role in a series of bank robberies and was also charged in absentia of the same kidnapping as his brother. The other escapee is an Albanian, serving time for manslaughter.
A manhunt is under way but catching them may take some time.
Nikos, the mastermind behind the plot, has been outrunning the police for 16 years. Now his little brother is with him.