Sherlock Holmes: The Devil's Daughter

During the ‘Chain Reaction case’, after you have gathered the suspects from the accident, and either before or after questioning the witnesses back at Scotland Yard, you need to find out where the technical cab came from. Your casebook hints that it may not have come from too far down the street from the accident.

Walk down the street where the crashed technical cab is. Using detective mode (), you will see mud tracks coming from a door on the left hand side of the street. Enter the shop and at the back is a locked door. For the first lock, use the #3 and #4/3 lockpicks. Then remove #3 and replace it with #4 for the second lock. Once inside the back room, press again to reveal mud tracks around a carpet. Press to pull the carpet away to reveal a ladder down to the sewers.

Once you are down in the sewer, follow the video embedded below to figure out how to control the water (there are a lot of steps). Once you complete this task, the achievement will unlock.

This achievement starts at [40:10] in the case walkthrough video in “Disaster Strikes.”