This is story-related, so it cannot be missed.
You unlock access to this mission when you complete all of the quests in Plankerton.
To unlock the achievement, you must successfully complete Storm Shield Defense 1 in Canny Valley (third area). It is just one 7-minute (maybe 8? can't remember) wave of level 46 enemies, quite a few blasters spawn. You need to defend just the central base. Depending on your level, you can tackle this solo+traps, but it's always better to go in as a team.