One hand wraps around his hand on the knife, the other on the handle. You curl your fingers around his wrist, tighening on the pressure points. The pain forces him to let go and in a swift movement you twist the knife around and stab him in his own stomach. Blood immediately starts pouring out and he collapses on top of you.
You notice everyone watching grimly. You realise you're in a bit of a pickle - hey you just killed someone in front of a lot of witnesses. You proceed to burst into tears.
"It was just a stupid movie," you sob, going into hysterics. "He didn't need to.. I could have... oh no..."
The whole matter is sorted out when you get to the next stop and you formally quit from the tour, saying that you couldn't bear to continue after such a traumatic incident. Everyone is sympathetic and no one blames you for wanting to leave.
Congratulations, Agent 437, you have competed your mission faster than we had anticipated. The agency of evil have one last agent to fo their dirty work.