Sam and Mark continue their search to find the world's next great superhero. Six superheroes remain in the lair.

The superheroes are called into action when Dr Dark attempts to contaminate the city's water supply.

The evil supervillain has released five barrels of toxic waste into the Thames and the superheroes need to get them back to dry land before they leak and before Dr Dark's pig-faced henchman returns.

The superheroes brave the icy water as they race to retrieve the barrels, but will they work effectively as a team?

Back at the lair, Sam and Mark put the superheroes' super senses to the test. Will they be able to identify pickled egg and chocolate ants by taste alone? And how will they cope when faced with the unknown during the touch test? Wearing blacked-out goggles, the superheroes are presented with a fake spider and a rubber snake. Will they demonstrate bravery? Will they overcome their fears? Or will their imaginations get the better of them?

Plus, one more superhero will be chosen to power down, return back to their secret identity and leave the lair for good. Show less