Aliens are coming! At the end of book four, Bob sent a signal to the GUNK Aliens telling them to invade earth. But there's no need to panic just yet - our hero Jack managed to weaken the signal, so they shouldn't get the message for a long time.
There's just one problem... other aliens are closer by, and they WILL get the message!
Now Jack and the gang have to get to Bob's base so they can use GUNGE's equipment to neutralise the alien threat. First, though they've got to deal with the strange creature that's terrorising swimmers at the beach. And then they've got an even bigger challenge - they've got to FIND Bob's base...