Verb
lose the thread (third-person singular simple present loses the thread, present participle losing the thread, simple past and past participle lost the thread)
(figuratively) To get distracted and lose track of something (one's train of thought, a conversation).
Because I find writing painful, I try to get it over with as fast as possible. But I write every day, or I lose the thread. Patrick Modiano
I try to do as many of my own stunts as possible. If you keep on taking yourself out of the role you play, you lose the thread of the character. Willem Dafoe