The aliens are upset that several humans brushed off their last challenge so easily. They would like to rectify this with a visible demonstration that their grey matter is indeed superior. Help to thwart them by determining the next figure in the following sequence:
You might find that it is easier to determine the pattern than to find the missing figure.
It might not help much, but:
The sequence cannot be continued after the missing figure.
If you are battling to get started, here's an oblique hint:
"Keep your friends close and your enemies closer."
-- Michael Corleone, in the Godfather II