Today's prompt from Wordwielder: Mud.
"Mr Holmes!" Mrs Hudson stormed up the stairs, an uncharacteristically fierce frown weighing on her face. She slammed open the door to apartment B, startling Holmes' guest into spilling her drink. "Mr Holmes, this is the third time this week I have had mud traipsed up through my front stairs. This must stop, today!"
Holmes leaped up, headed straight for the stairs. "Where is the mud? Quickly, Mrs Hudson, this could be essential to the case!"
"All the way up my front stairs, Mr Holmes, I just told you that!" she growled. "Do you listen to a word I say, young man?"
Holmes was too occupied to take any notice, his magnifying glass just millimetres away from the muddy stairs. "A curious colour, so dark as to be almost black, and with a very fine consistency. Watson!"
Watson appeared at the top of the stairs, a comforting arm around their very distraught client. "Have you found it, Holmes?"
"Yes, this is it, exactly the clue we needed!" He turned to the young lady. "Miss Gardner, we must leave immediately. I know exactly who killed your uncle, and if I am right, they will kill again. We must be off!"
All three ran down the stairs and out the front door, leaving Mrs Hudson fuming behind them. "Mr Holmes, this better be the last of this, or next time, you will be the one cleaning these stairs!"