Near the
end of the
level you will
reach a large wall that requires detective mode's thermal vision to
unlock a switch, after you jump through the door pay close attention to the large SILER LEGO plate on the ground, destroy it to open a portal to the secret area.
The more you play, the more ably you'll grasp your options in a given situation, so while gamers
of any skill
level can
reach the
end with little difficulty, there are ways to separate from the pack with speed runs (
unlocked after initially completing the game).