In their famous paper Fox and
Artin constructed several examples of wild cells in 3-space. The present authors
construct a wild disk D in the 4-sphere S4 with the property that the proof of
nontameness is perhaps the most elementary possible. We require only the knowledge
that if K is the trefoil knot in the 3-sphere S3, then the fundamental group
π1(S3−K) is not abelian. Parenthetically, the wild disk D constructed here has the
property that every arc on D is tame, a fact which follows immediately from the
construction.