Each episode of Tragedia Endogonidia opens with a kind of breathing, as though there were a membrane between the stage and the auditorium through which, once we begin, breath may pass, that deep breath we take before we take the plunge. 

(我的翻译)《无尽繁殖的悲剧》的每一集都以一种呼吸（breathing）开始，就好像在舞台和观众厅之间有一层薄膜。一旦我们开始，呼吸，那种我们在冒险之前会做的深呼吸，就可能通过这层薄膜。

每次一看到插入语多了，句子结构就分不清了。请问老师红字部分是主语的补语吧？

谢谢老师