MC1 simply cannot bare the loss of her sister/best friend/mother/brother. So she frantically searches for a way to bring them back. MC1 gets a hold of a remedy/ritual/etc that brings back her loved one from the dead. Story could go a ton of different ways… 1) Person comes back normal at first, showing up like nothing ever happened. Then slowly starts to become hungry… until finally they’re taking off a chunk of mailman flesh as he slips the mail through the slot….. 2) They could come back as something else entirely…. already a zombie that starts the ole’ apocalypse scenario….
EDIT: Also can reverse this and write in 1st person… from the point of view of the character that was brought back from the dead. Start with them waking up in coffin and making their way back to home. See the reactions of people who know them, etc….