The Master Key 

A building full of secrets. A key that will unleash them all.

The K Apartments for Ladies in Tokyo conceals a sinister past behind each door; a woman who has buried a child; a scavenger driven mad by ill-health; a wife mysteriously guarding her late husband's manuscripts; a talented violinist tortured by her own guilt. The master key, which opens the door to all 150 rooms, links their tangled stories. But now it has been stolen, and dirty tricks are afoot.

For a deadly secret lies buried beneath the building. And when it is revealed, there will be murder.