You kick off your IMPORTANT MISSION by utilizing the oldest SPY EQUIPMENT known to mankind: The raw, unadulterated SENSATIONS afforded to you by your SENSORY ORGANS.
Everyone has a smell unique to themselves. The Seconds twins are no exception. If you can just latch on to their SCENT...
...The only thing the dirt smells like is dirt. Maybe the twins conceived of a dastardly manner of cloaking their SCENT. Maybe your nose needs a tune-up. Maybe this is a stupid idea.