So that proper key had to be at the other end of the connection.

"Most situations merely respond to the proper key, if it can be found," the tree said.

The path of storms can be predicted; you merely have to know the proper key.

The proper key is, in fact, hiding amid all of those.

Well, it hadn't been a proper key, not in Jim's opinion anyway.

Unless unlocked with the proper key it will blow your head off.

I have convinced the alarms that we hold the proper keys.

After several tries he found the proper key to admit him to the jail.

Wilkerson rose from his chair and pulled the proper key off the wall.

Now if she just had some notion how he could have gotten into a locked room without the proper key.