Pretty simple genre work from Johannes Roberts. Of course, that's what he's known for, though his later films do seem to have a bit more quality to them. Storage 24 is really baseline, sticking to a couple of familiar clichés and adding very little to them. If you're looking for some creature flick filler though, it's not the worst film out there.
When a plane crashes down in central London, a mysterious cargo falls next to a Storage 24 facility. The facility goes into lockdown, trapping a handful of people inside. While tensions between the group are already quite high, things are about to get a lot worse when they find out what escaped from the plane.
Roberts does a fairly decent job building up the tension. The creature effects/design are pretty crummy though, which makes it difficult to really get into the film. Performances are basic, and the plot is really thin, but the film does have a handful of decent moments. Not great, but not entirely worthless either.