A key, a casket and the hunt for Spanish dramatist Pedro Calderón's bones

Dogged detective work and radar scans of a church wall may help find the last resting place of the great playwright

The death of Pedro Calderon de la Barca - soldier, priest and one of the finest dramatists Spain has produced - continues to prove almost as turbulent and unpredictable as his long and improbable life.

Four centuries after Calderon died in Madrid aged 81, researchers believe they could be close to finding his remains, thanks to the deathbed testament of a priest, a key long guarded by the playwright's family and the latest in ground-penetrating radar.