Doctor Who

Desperately you look around, hoping for something that could help you or Rose, but the only things with you are the sonic screwdriver and a gas mask. You try to open the door, but it is deadlocked, and even the sonic screwdriver has no effect on it. Suddenly you realise what needs to be done. You look up at Rose's face and her gaze meets yours. Her eyes widen as she realised your intentions. A tear escapes and silently rolls down her cheek. You strap the gas mask over her face just as the gas reaches full power. Rose screams "Doctor!" but no sound escapes the mask. You collapse onto the floor, gasping for breath...