When Dogged Detective enters the battlefield, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Whenever an opponent draws their second card each turn, you may return Dogged Detective from your graveyard to your hand.
Dogged Detective doesn't need to be in the graveyard when the first card is drawn for its last ability to trigger. As long as it is in the graveyard when an opponent draws their second card in a turn, it will trigger.