Just watch...

Unfortunately, helping would be suicide. You have no other choice than to watch. You try not to think about what is about to happen to the poor woman in front of you right now, but you will have a front row ticket. You hope you'll be able to live with yourself for letting this happen to her.

"Help! I beg y-"

Her cries are silenced when the zombie plants her naked foot right atop the woman's face. She protests, muffled, beneath the infected sole, arms flailing and trying to pry the zombie's leg off. But, it is to no avail; the more she struggles, the quicker she will be infected. Then, after she is infected, she only needs to orgasm to turn. And she will probably be more than happy to play along with that.

Looking around, you see that all the zombies are preoccupied with other victims right now. It'd be a good opportunity to make a break for it.