Battle's End

From publisher blurb:

A 6-Pack Adventure: pick-up-and-play adventures designed to fill 2-4 hours of play and containing everything you need!

Battle Map
Tokens
Pre-generated characters

For longevity you can use the tokens and the map for anything else you care to do and the adventures should be fairly easily adaptable to fit into your existing campaign if you want.

Battle's End has a group of adventurers taking their rest from their individual wanderings in an inn, The Battle's End. Their rest is due to be interrupted however as the village comes under a mysterious assault by the legions of the undead...