6/6 Richard and Door finally discover who ordered the death of Door's family. Can they escape?
BBC Radio 4 Extra
5/6 Richard and Door find a guide to lead them through the labyrinth deep beneath London.
4/6 Richard heads to the monastery where he must undergo a terrifying ordeal to obtain the key
3/6 Richard and Door travel to the British Museum to locate the citadel of the legendary Angel
2/6 To learn who killed Door's family, Richard visits a venerable resident of London Below.
1/6 An act of kindness catapults Richard from his ordinary life into a subterranean world.
BBC Radio 4