Private Eyes, Apple Tree Theatre. The trouble with Steven Dietz’s intermittently clever jigsaw puzzle is that he seems far less concerned with the pieces than with how they fit together. Forsaking typing paper for graph paper, he’s fashioned an impossibly complex labyrinth around a rather banal, undeveloped love triangle: the relationship of a husband-wife acting team is shaken by the wife’s dalliance with a smarmy British director. Dietz’s adroitly paced play strips away layer after layer of artifice, but it never arrives at any naked truth. Is Lisa’s infidelity an illusion? Is it part of a play within a play within a play? Is it a fantasy acted out at a therapy session? These questions might have been more compelling if Dietz had given us living characters instead of sketchy shapes on a flow chart or if his observations on truth and theatrical role-playing weren’t quite so familiar.