According to the Daily Star, David (Jack P Shepherd) is set to crank his evil ways up to a new level when he pushes Gail down the stairs. And this isn't an accidental push - a "Corrie insider" says, "[David]literally throws Gail down the stairs and she is knocked out cold." The reason for this behaviour is that Tina aborts the baby she's expecting, without telling David she's pregnant. When he overhears Gail and Tina talking about it, he sees red and blames her. “These are some of the most dramatic scenes of the year," says the insider. "David’s rage is off the dial. Normally he takes his time plotting revenge on his enemies but on this occasion he snaps."
Gail recovers from her physical injuries, apparently, but her memory is affected, and David takes advantage of this to play evil mind games with her. Echoes of Richard Hillman there.