Yeah, but...IMO, we'd need to see that, because something would have happened to tip someone or other off, leading to some kind of confrontation. It could be used as backstory material next season, but at that point it'd really just be filler and (again IMO) we already get too many filler eps.
Drugged food ftw! (
skimom2's suggestion of them being taken in their sleep. As for how...there should be plenty of plants readily available that could be used, if you knew 'the old ways'.)
On another topic, the food thing has always bugged me slightly. The supermarkets might be empty due to panic-buying as the crisis developed (or maybe not)...but there are warehouses and ordinary dwellings where the store supplies would have ended up. Personally, I'd be foraging away, stacking up on concentrates and canned goods. I'd get a scoped rifle, a shotgun ("for close encounters"), a couple of handguns, a hunting knife or two, an axe, maybe even a crossbow, and all the ammo I could carry (and I can carry a bit more than my own body weight in a rucksack or two - or used to be able to, at any rate!). Then I'd find me a place up high - a bell tower or attic space, anywhere I could weigh down the hatch and/or command a decent field of view - rig up a couple of water butts to catch the rain, and appropriate a fair bit of gas and a camping stove. Not forgetting cling film, of course.
Et voila, I'm good for months if not years. Long enough for the rotten bar-stewards to finally fall to bits.
(I'd also get a suppressor or two for my weapons, since big loud bangs attract the undead.)
