It's Sciency-Wiency stuff!

The end?

Matt cornered the women, eyeing Alice accusingly the whole time. "I didn't do it on purpose, Matt...." she whispered apologetically. "I'm not doin this on purpose either, love! " he muttered mockingly, before grabbing her by the neck. Madeleine felt her legs turn to jelly and her voice betray her. Alice felt the ground give way from beneath her as he raised her up, applying pressure to her throat as he tightened his grip. She swatted at his arm, trying to loosen his hold on her, while her other hand clutched on to the syringe. She peered at his monstrous face and into his terrifying, bloodshot eyes and knew that the timid man was still in there somewhere, fighting against it....but, he couldn't do it alone. 

"I'm bringing back the man I loved! " she squeaked, as she raised a trembling hand and stuck the needle into his neck. She smiled triumphantly on injecting him with the antidote, but her smile quickly faded away as an irate Matt lashed out, tossing her away violently over the railing of the bridge, before pulling out the syringe with a groan and rubbing at the needle mark on his neck. He felt himself changing, as the spines fell away and he returned back to normal. Of course, by normal, it meant that he was back to being a paralyzed man. 

He raised himself groggily on his elbows and remembered what his rage had caused as he watched Madeleine cup her hands around her mouth, calling out to his wife- her wide, worried eyes searching the dark waters for her. "There's no sign of her. I'm sorry, Matt...." she mumbled apologetically, turning towards him on noticing him. " No...Alice...noooo!" he moaned, leaning back against the cold steel railing and letting tears roll down his cheek as he blamed himself for what had happened to her.
Martin and Deirdre, who'd reached the footbridge just then, joined in the search. "There she is! " Deirdre exclaimed from a far end of the bridge, spotting her thrashing about and pointing her out to the others. She was trying to stay afloat, while weakly yelling out for help. Martin was still recovering from his injuries and Deirdre was a hydrophobic. Someone had to save her before the river claimed her.