Her boyfriend's screams were ringing in her ears and she was running in total panic, unaware of where she was going. She stumbled over a pointy rock and cartwheeled down a steep hill. Martha crashed into the base of a small tree, but at least it stopped her fall.

In a daze, she managed to pull herself up. Jesus, she was pretty sure she'd broken her right arm. Cradling it with the left, she ran forward in a clumsy stumble.

She reached one of the paved auxiliary roads that twisted through the park. Davis's screams had stopped. What had happened to him? She had to get help.

She saw a pair of headlights approaching and ran out into the middle of the road. She straddled the double center lines and felt like a total madwoman. For God's sake, this is San Francisco!

'Please stop, please stop. Hey! Hey! Hey!' She waved her good arm and shouted at the top of her voice.'Stop! I need help!'

The white van sped straight for her, but then, thank God, it skidded to a stop. Two men jumped out and ran to her. They would help. The van said 'Red Cross' on its hood.

'Help me. Please,'Martha said.'My boyfriend is hurt.'

Everything went from bad to worse. One of them hit her with a closed fist. Before Martha realized what was happening, she went down hard. Her chin struck the pavement, bouncing like a wet ball. She was knocked almost unconscious by the powerful blow.

She looked up, tried to focus her eyes, and wished she hadn't. Blazing red eyes stared down at her. A mouth was open wide. Two mouths. She had never seen such teeth in her life. They were like sharpened knives. The incisors were huge.

She felt the teeth bite into her cheek, then her neck. How could that be? They tore into her and Martha screamed until her throat was raw. She rolled and twisted and kicked out at her attackers, but it did no good. They were incredibly strong. Both of them were growling.