Be quick." Drawing a long breath, Tuppence entered the Mansions and ran up to the door of No. 20.
Tuppence ran up the second floor to door No. 20. 
mnli hypothesis: Tuppence ran up the second floor to door No. 20.  premise: Be quick." Drawing a long breath, Tuppence entered the Mansions and ran up to the door of No. 20.