The ratio of people to cake is too big.
Excuse me, I believe you have my stapler...
When your partner puts a disc on a location, that means one of your elements is there. When they put a cube, it means one of your elements is adjacent. Buy since it's general, and not about a specific element, i'm confused as to how you narrow down what your three elements are.
When you place an investigator. Up to 3 pieces of wood are placed in the location space above the 3 boxes.
When you select an evidence card. One (or zero) piece of wood is placed in the specific box (depending on the type of evidence).
You need to use the evidence to help you figure out which cube or disc from your investigator applies to which box.
For example, you have played a downtown evidence card and were lucky enough to receive a disc there. If you have an investigator at Central Station with a disc and a cube, you now know the cube applies to the location (since Central Station is next to Downtown). Now you just have to figure out if the disc applies to the person or the crime.