So when Sarah Jane and Rani decided to go the Nuclear Power Station they left Clyde in charge of Sky. So when Sky was at home with Clyde she began to cry and messed up Clyde's phone pretty badly however a metal kind was after Sky since she was a weapon against the Metal Kind. Clyde dodged its blasts and ran into the van that was brought by Sky's mother. At the Power Station Sky's mother asked Clyde to give back her baby, but when Clyde refused and ran away she got really angry.
A meteor crashes in the middle of a junk yard to reveal a metal man. Meanwhile, Sarah Jane discovers a baby on her doorstep in the middle of the night who can create power surges. Sarah Jane calls Rani and Clyde over for them to help her and after Clyde shows his paternal side, Sarah Jane and Rani travel to the site of the meteor crash. There they are met by Professor Celeste Rivers who investigates the site with them. Sarah Jane and Rani find a homeless man who saw the metal man and describes him to them; they then discover that the metal man is heading to Bannerman Road.
Meanwhile an alien woman named 'Miss Myers' appears at a nuclear power station and discovers that there was a power surge in Bannerman Road. She makes her way to the Chandras' residence and Gita announces that Sarah Jane has just fostered a baby, as Gita had seen Sarah Jane earlier. Miss Myers makes her way to the garden where Clyde and the baby named Sky are to discover that the metal man is about to attack them. Miss Myers saves Clyde and Baby Sky and takes them to the Power Station. Miss Myers reveals that she is Sky's mother and is also an alien.
Sarah Jane and Rani return to the house to discover that Clyde and Sky have gone. Mr Smith locates Clyde at the power station and Sarah Jane and Rani make their way to the station. They find Clyde, Sky and Miss Myers who reveals that her species, the Fleshkind, are fighting a war against the Metalkind. She also reveals that Sky is a weapon who will put an end to the war and as she says this the metal man walks in. Sky then transforms from a baby into a twelve-year-old girl.
At Miss Myers' command, Sky unintentionally attacks the metal man with a burst of energy. Miss Myers reveals that Sky was made and "grown" in a Fleshkind laboratory as a weapon to destroy the Metalkind. Sarah Jane and the gang escapes with Sky before Miss Myers could get ahold of her. Miss Myers then tells the metal man he would help her get Sky and has him wired up.
Sky, who is still experiencing the world and words around her, is brought into the attic where Mr Smith scans her. He concludes that Sky's metamorphosis was caused by her synthetic DNA and was done to maximize her effectiveness as a bomb. Full activation would not only destroy the Metalkind but Sky herself as well. Although there is no cure for the energy from the Metalkind's presence would activate Sky's power, she can still be "defused". However, only Miss Myers can disarm her genetic trigger. Sky agrees to go there, stating that she might die anyway.
Back at the power station, Sarah Jane tells Sky to stay with Clyde and Rani. With the absence of Sarah Jane at the time, Sky escapes, running inside the factory, trying to help Sarah Jane. Meanwhile, Sarah Jane, who is taken to Miss Myers, learns that the damaged metal man is wired up to the nuclear core in order for him to act as a homing device. Miss Meyers also reveals she reprogrammed his mind as he swears veangance on all flesh kind, including Earth's inhabitants, thus bringing their war to Earth. Believing that the Metalkind will be destroyed upon their arrival on Earth, she activates the calling of the Metalkind. Downstairs, Sarah Jane meets up with Sky, who tells her she must save Earth and goes up to the nuclear core room. Sarah Jane then orders Clyde and Rani to shut down the nuclear reactor in the control room before heading after Sky, whose activation started from the presence of the metal man and Metalkind's portal opened by Miss Myers.
In the control room, Clyde and Rani discover the Nuclear Rod Regulation System and removes the rods based on the order of the visible spectrum. They were successful in closing the reactor as the portal closes with a large power outage. The energy from the portal backlashed on Sky, destroying her genetic programming as a bomb. Miss Myers doesn't want the child anymore for she is no longer a weapon. The metal man, who reveals that he saved some of the portal's energy, breaks loose and uses the energy as he takes Miss Myers with him.
Sarah Jane explains Sky's appearance to Gita and Haresh back at Bannerman Road, telling them the adoption agency had a mixup. Some traces of Sky's electric powers are still present. In the attic, Sarah Jane finds the Shopkeeper and the Captain, previously met in Lost in Time. He reveals it was he who placed infant Sky on her doorstep. The Shopkeeper, answering Sarah Jane's question of their existence, tells her that he and the Captain are "servants of the universe". He then gives Sky the decision to leave with him in which she declines and stays with Sarah Jane as her adopted daughter. He then disappears before Sarah Jane could ask him any further. She then says they will find out who he is soon....