The locked door of a vault, with the key lying on a table beside a dead man, presents Superintendent Carver with a baffling case of murder, for he must find how the murderer managed to lock the door and replace the key on the table!
| Name | Type | Role | |
|---|---|---|---|
| Paul Daneman | Guest Star | ||
| Bernard Archard | Guest Star | ||
| James Villiers | Guest Star | ||
| Allan Davis | Director |