Secret Avengers #18

Aside from feeling far more like an Authority story than an Avenger story, the comic is pretty good including a well-designed M.S. Escher like world for our heroes to battle the members of the Shadow Council.
Writer Warren Ellis even gives us an appearance by Arnim Zola (a perfect villain for this type of story), the return of the Beast (who is given most the of monologue necessary to explain the situation), and a fun cameo by Reed Richards which allows the comic to end with Steve Rogers delivering a joke. Worth a look.
[Marvel, $3.99]