Langdon’s performance, however, can get you through most any rough patch. He delivers Christopher’s speech in strange singsong, his incantatory rhythm showing just how much Christopher travels on his own frequency. He radiates appeal, with an almost undetectable smile as he matter-of-factly ranks his likes and dislikes, his prowesses. Elliott’s staging makes him magical, even. An ensemble of actors makes props appear exactly when Christopher needs them; they send him aloft both in moments of intellectual reverie and bottomless terror.