cubes.â
âHow do you know there are six?â Josh asked.
âBecause when I was clearing out the shelves of my old lab, I found this,â Petty said. She held up a small box covered in blue velvet. It looked much like the square red and green velvet boxes containing the BUG and REPTILESWITCH cubesâbut this box was round. Inside there was a ripple of some silky blue material across six round dents. In three of these, Petty had pressed the first three marblesâred, green, and blue. But the other three dents were empty.
âSo ⦠did you hide the marbles the same way you hid the REPTOSWITCH cubes?â Danny asked. âIn case Victor Crouch double-crossed you and came looking for them?â
âI donât know,â sighed Petty. âObviously that bit of memory is burnt out, or I would have thought to ask you to look for these when I asked you tolook for the REPTOSWITCH cubes in the summer. And anyway ⦠if I did hide them, somebody else has clearly found them. Or more likely, stolen them.â
âWho?â Josh asked. âVictor Crouch again?â
Petty reached behind her and took down a wooden frame. In it, much to their amazement, was a photo of Victor Crouch. He was wearing a black hat and waving cheerily at the photographer, the one spiky black fingernail on his little finger pointing up into the air. Had he possessed any, his eyebrows would have been raised. But as peculiar as Pettyâs old nemesis looked, it was something else that made them gaspâhe had his arm around none other than Petty Potts.
âYes,â sighed Petty. âThis was when we were friends ⦠or so I thought.â
The Petty in the photo looked about ten years younger. Her hair was darker, and she had one or two fewer chinsâand those chins were definitely less whiskery. Someone elseâs hand was tucked through the crook of Pettyâs left arm, but they were cropped out of the picture.
âThis was taken while we were working together in the secret government laboratories,â remembered Petty. âLittle did I know that only a year or so later, he would have framed me in a very different way! And lost me my job and tried to steal all my genius work! I also found this while clearing out the old lab. I keep it to remind me never to trust anyone! You hear me, boys?â Her voice became shrill as she started bashing the picture against the wall. âNever trust ANYONE! NEVER, NEVER, NEVER!!!â There was a tinkle of broken glass.
âO ⦠K,â Josh said, stepping away. âSo ⦠no other ideas about who the Mystery Marble Sender is?â
âNope,â snapped Petty. âWere there postmarks on any of the letters?â
âOnly on one parcel,â Danny said. âAll the others were hand deliveredâapart from one which came on a parachute. The parcel had a London postmark. It was a set of books Josh had won in a wildlife competition with Chatz TV. A clue was tucked in with it.â
âLondon ⦠hmmm. Well, thatâs not much help,â grunted Petty. She slapped the broken picture frame facedown on her workbench. âNo idea at all! And even LESS idea why this Mystery Marble Sender is sending them to YOU two. Go onâgo on home now and see if there have been any more clues! Keep watch! Never rest! Watch from behind your curtains at ALL TIMES! If you watch all the time, sooner or later the Mystery Marble Sender will slip up and youâll SEE him!â
âFine,â Danny said, grabbing Joshâs arm. âWeâll go now.â
He and Josh left Petty shouting at the broken picture frame and let themselves out. The door at the foot of the stairs had a deadlock that they could open from the inside, so they got back out into the lobby and then left it to fall shut behind them. The only way back in would be if Petty opened itâor if they S.W.I.T.C.H.ed again.
âWatch from behind our