The investigation has been going on for months, and we're still 'none the wiser' about the true cause of the accident. [=we still don't know anything more about the true cause]
I'm 'wise to' you. = I'm 'wise to' what you're doing. [=I know what you're doing; I know that you are trying to do something dishonest]
I borrowed his car and returned it, and he was 'none the wiser'. [=he did not know that I had borrowed his car]
(..) dependent on a Northman. They tend to tell the truth. Your grandfather warned against them. He said they were the greatest threat against his empire. My grandfather, wise as he was, great as he was, did not understand everything. Times change. But the threat of the Northmen remains! (..)2016 TvShow: Vikings Title: The Last Ship Season: 4 Episode 10