Maurice Leblanc,
The Crystal Stopper — Chapter II: Eight from nine leaves one
(1912)
“ Now Gilbert was in prison. Was Lupin to suppose that Gilbert had betrayed him and put the police on his tracks? In that case, why were they content with taking the crystal stopper, instead of arresting him, Lupin? But there was something much stranger still. Admitting that they had been able to force the doors of his flat--and this he was compelled to admit, though there was no mark to show it--how had they succeeded in entering the bedroom? He turned the key and pushed the bolt as he did every evening, in accordance with a habit from which he never departed. ”
