In the Intro to "Daryl's Ambitious Card Omnibus", Stephen Minch says, "...the Ambitious Card is a classic trick--one of the most popular card effects of all time. Since its invention, an impressive amount of paper has been spent on the card that rises, time after time, to the top of the pack".
He seems to assume readers of that book are already familiar with the plot as he doesn't describe it further.
"Dai Vernon's Ambitious Card" appears on page 76 of "The Stars of Magic". There, the effect is described as follows:
"A card is repeatedly placed into the center of a pack and caused to jump invisibly to the top or bottom. Whenever the spectator thinks he is following the magician's actions, he nevertheless finds that he has been completely bewildered."
Now, if you're asking how Daryl frames and presents the effect, that is another thing entirely... ;)