Shock doc: In case your fear of doctors isn’t what it used to be, the Mammals Theatre Company revives “Clay Continent,” a horror play about a doctor’s desperate attempt to crush his own demonic possession. The show draws on excerpts from Robert Louis Stevenson’s “Jekyll and Hyde,” Fyodor Dostoevsky’s “Notes from Underground” and several Edgar Allen Poe stories. 8 p.m. Friday and Saturday through April 26. $10. Peter Jones Gallery.