This is a bonus cache you can find after completing the nearby "Downtown Palatine" adventure lab!
Do the adlab here!
The final here doubles as a Trackable hotel for the Palatine area!
You can find the final here:
N 42° 06.LMN W 88° 02.OPQ
L=A+C
M=B+F
N=E-D-F
O=A+C-B
P=D
Q=C-F