Read it through once

Still more shaken was he next morning. They had sat down to their breakfast when Lucy with a cry of surprise pointed upwards. In the centre of the ceiling was scrawled, with a burned stick apparently, the number 28. To his daughter it was unintelligible, and he did not enlighten her. That night he sat up with his gun and kept watch and ward. He saw and he heard nothing, and yet in the morning a great 27 had been painted upon the outside of his door.