At this moment there was a light, discreet tap on the door.

A discreet tap on the door surprised her.

There was a discreet tap at the door.

A discreet tap on the door reminded her that they were not alone, thank the saints.

A discreet tap at the door to her office made her look up.

A discreet tap on the door heralded the arrival of the medical team.

At one a.m. there was a discreet tap on the door.

There was a discreet tap at the door; it opened and the young Third Secretary poked his head in.

Their papers were already put away, and the map locked from sight, when there was a discreet tap on the door.

Besides' He broke off as there was a discreet tap on the door and the housekeeper came in carrying a tray of coffee.