Related Clues:
- Secret lock uncovered by sect
- Could mostly act deviously, unable to keep a secret
- Mysterious copper squashed between two officers
- Tsar can earn mostly in secret
- Officer commanding sect in supernatural forces
- The black stuff perhaps is least taken from coal scuttle?
- Unfamiliar to most
- Grasped by few
- Understood only by the few
- Relatively unknown
- Strange commander leading line into trench
- Requiring rare knowledge
- Black arts of old Conservative party
- Cryptic formula for caustic soda in use, last of all
- Mysterious beggar can enter houses