Mr. Ballard plays two themes in ["Concrete Island"]. The external theme is the Robinson Crusoe gambit—a foolproof narrative ignition. (How can a maimed motorist survive for days on a devil's island rimmed by traffic?) The internal theme is the search-for-self motif. (What is Robert Maitland really like?) Mr. Ballard fades in the second when he introduces a couple of surprise tenants of the concrete island: Proctor, a brain-damaged acrobat, and Jane, a social dropout. With these two Beggar's Opera types as companions, the architect's tenure takes on a surrealistic air. What do they want? What does Maitland want—besides Out? Mr. Ballard raises some tantalizing questions, even if he doesn't answer them satisfactorily.