Thread ID Variable

[Kybyrian]

I'm using a plugin with the hook newpost_complete and am trying to set a conditional for a certain thread, but I can't seem to find a variable that specifies the thread id of the current thread.

I've tried $thread['threadid'], $threadinfo['threadid'], $post['threadid'], and $threadid, but neither of the four have worked at all. What variable would specify the ID of the current thread that I could use with this hook?