Recap: The Sarah Jane Adventures S2 E9-10 "The Temptation of Sarah Jane Smith"
Sarah Jane and the gang discover a fissure in time, leading to the day of August 18, 1951, the day that Eddie and Barbara, Sarah Jane's parents died in a car accident, while Sarah Jane herself as a baby was left in her pram on the side of the road. Luke thinks that it is a trap, but ends up following Sarah Jane through it anyway. She uses her Sonic lipstick to deactivate their car, and suddenly a storm begans to brew.
It turns out that it is
a trap, set by none other than the Trickster, because the death of her parents was a fixed point in time, and the altering of it smashed open the Web of Time, allowing the Trickster to manifest himself on Earth.