Problem progressing in the game

[Jon.Topps]

I'm having trouble progressing. We've beaten all the levels on the map, except for one (The Big Grapple), because when we click it, you can't actually play the level (it's not available for some reason). There are NO other levels on the map that we haven't beaten, we've done them all, and we've done a ton of the freeplay aspects too.

There is no computer to unlock characters yet, and from what I've read online you have to progress in the story to a certain point, and then the computers will unlock. But there's nowhere to go to progress!

We did the stuff that leads to space, and you save the space station and whatever, but we haven't yet defeated Brainiac, but I don't see any levels or anything to do that. At this point I think my percentage is like 11% or something, and there's very little left to do that we have access to.

Where are we supposed to go, and what are we supposed to do, in order to progress?