The candidates talked about the people they met on the 'campaign trail'. [=the people they met while going to different places during the campaign]
As he gained more political power, he left a 'trail' of bitterness behind him. [=he treated people badly and made them feel bitter]
The police are 'hot on the trail of' the escaped convicts. [=are chasing the escaped convicts and are close to catching them]
(..) No. If we are to get away from here, we must find another way. What exactly do you propose? Sauni're was reading his book. "Blood trail." Excuse me, captain. Crypto called. They identified the code. Neveu told us already. I should have fired her on the spot, (..)2006 The Da Vinci Code