Walkers beware! You may not want to take a shot at this one...
Kevin Spacey is Francis Underwood?
The reference is to
House of Cards, where Kevin Spacey played the character of Francis Underwood.
The following line contains spoilers for both this puzzle and the underlying reference.
"Walkers Beware" is a reference to Garrett Walker, the president of the US before Underwood, whose resignation was brought about by Underwood.