Right, right, next chapter. So, where's the last mission clue? Thanks for reviewing, Ninjatana Warrior.

There were only two more areas upstairs where the mission clues could be hidden. Botley pointed out everything. "The tram is the only way to get up and down for this floor. These are Professor Spark's major inventions. On the left is the observatory – you know, it has everything about space and the stars? Although last month, the Professor caught Polly using the telescope to spy on the neighbours. She got in major trouble." He sighed happily. "I wish he was here more, then Polly wouldn't get away with anything. She listens to him, most of the time. Anyway, on the right is the robot maze. It's used as kind of a training ground or boot camp to test robots when they're first made. That includes me – I passed with flying colours when I was tested, but sometimes there are robots that need bugs worked out before they can be let loose."

I frowned. "Are you sure you passed first time? Maybe you just don't remember the first time because you had some bugs that made you forget. And if you think I might doubt you because you didn't pass, I won't."

Botley didn't even take offense to my suggestion. He just laughed. "Well, if I did have bugs and forgot, I wouldn't be able to tell you, would I? But Professor Spark mentioned that was my first time around the course. I've had one or two computer viruses since, but those are easy to delete." He shrugged. "And I guess I should mention those stone doors at the back. That's where the time machine is. But that'll have to wait."

"So where's the last clue?" I asked, eager to finish the case.

Botley shushed me. "Just let me sense out the area." Soon, his anntenae bleeped, and he said "It's in the robot maze." Then he smiled. "Well, at least I know the test route robot is in there, so I won't have to go on the course again myself. Professor Spark uses it to test out routes so that if the robot does the route correctly, the maze should go fine. The tester doesn't have any emotional intelligence, so all it can do is follow orders."

We entered the robot maze, a rocky balcony. There was a little gate to go down to the actual maze, which was a set of rocks, logs, bridges and a little red box in the corner. On the balcony was a little tablet that had a list of instructions of directions, like "4 South" and "Log West". As Botley had said, a little robot with a vacant smile was standing in the corner opposite to the little box.

"The reason the Professor uses this part of the mountain is because it's the most dangerous." Botley explained. "Luckily, he can save any of us if we fail to follow the commands. But it's so scary that even the robots like me who have free will wouldn't dare screw up here.

At that moment, one of the monitors arrived. Polly wanted to explain what was going on. She confirmed that there was a clue in the red box. "I got that stupid robot to put the box where you wouldn't be able to reach it. Then I scrambled the commands. See if you can unscramble them. Too bad it wasn't in the observatory, huh, Space Case?"

Before I could argue, she was gone, and I looked down at the commands on the tablet. "So all I have to do is put the commands in an order so the robot can get to the box?" I mused. There were only five commands. The robot could walk across one log, and jump over one part of the gorge, but apart from that, I'd have to just let it walk south-west.

It was fine, making it walk south to get to the log, get on the log and walk west, then walk a few more paces south, but then I made it walk further west, then jump south. That's where the problem began. I actually failed, because it went one pace too far and fell into a crevice.

"Poor little guy." Botley sympathized. "Either he's really brave, or really stupid. Probably both." He saw my look of disappointment and put a metallic hand on my shoulder. "Don't look so down, Grace. You've done really well on the last few challenges. You just mixed up one command. You'll get it this time."

I managed a smile. "I hope."

As it was, Botley was right. I just needed to have the robot jump once it got southern enough that it couldn't pace any further, and then walk on the outside to the corner where it picked up the box, and was then brought up to the balcony by a magnet, where I was able to take the last clue – a tablespoon. And as Botley had guessed, we had just enough invention points to open the time machine.

"Are you ready?" Botley asked as we stood outside the stone doors.

I took a deep breath. "I think I am. It's just...you know, you read all about time travel in books and things. I can't help wondering what will happen if we screw up."

"There's a very small chance that will happen." Botley said reassuringly. "All we have to do each time is recall the robot before they even got to that part of history. We don't even have to leave the time machine to do that – we just watch through a window. Professor Spark's used the time machine before, and nothing's changed. But," he smiled, "I'm nervous too. In fact, I'd kind of be grateful if you'd hold my hand while we go in."

I wondered if he was just saying that, but I did feel a bit calmer with the metal hand clinging on to mine. We walked up to the doors, and as they slid open, I blinked at the bright light in the room. But the only thing I had eyes for was the futuristic giant flying saucer in the corner.

Sorry. No. Not a flying saucer.

The time machine.

The Wheel Of Invention will be in the next chapter. Believe it or not, Grace won't actually get to my favourite activity of the game until after she's finished this mission. Question – which mission's concept interested you the most? I kind of liked the paper, the chewing gum and the use of money.