This is a guide to find a way to bypass the security door in Chapter 2 Dust to Dust in Thief 2014.
Get the Key for the Security Door
To bypass the security door steal the key from the Baron’s Highcollar that is inspecting the bodies as they come by:
Wait for the guard near the Baron’s Highcollar to be away from the Baron’s Highcollar and jump up to the platform.
Bypassing the Security Door
Steal the Machinery Room Key from him. Use they key on the silver square beneath the notice next to the door to bypass the security door: