Maria Jackson has just moved into a new house with her recently-divorced father when she becomes aware of strange goings-on involving her reclusive neighbour, journalist Sarah Jane Smith. But things get even weirder when Maria's new friend, Kelsey, invites her on a tour of a factory which produces the mysteriously addictive energy drink Bubbleshock. There, Maria rescues a strange boy, and has nowhere to turn but to Sarah Jane herself. Together, they must discover the connection between Bubbleshock and an alien plan to conquer the Earth.

Elisabeth Sladen originally played Sarah Jane Smith in Doctor Who between 1973 and 1976. The character quickly became recognised as one of the programme's archetypal companions, to the point that Sladen was invited to return to Doctor Who and reprise her role as Sarah to ease the transition between Fourth Doctor Tom Baker and Fifth Doctor Peter Davison in 1981. Sladen refused that offer, feeling that it would be a backward step in her career to resume playing second-banana to the Doctor, but subsequently agreed to take a starring turn as Sarah Jane in a spin-off series, K-9 And Company, which was being created in response to the public outcry over the departure of robot dog K-9 from Doctor Who in Warriors' Gate. Unfortunately, K-9 And Company did not survive past its December 1981 pilot episode.

After a brief return to Doctor Who in the 1983 twentieth-anniversary special, The Five Doctors, Sladen largely put her television career on hiatus in order to raise her family. Nonetheless, she lent her voice to several audio plays, portraying Sarah opposite Jon Pertwee's Third Doctor in the BBC Radio broadcasts The Paradise Of Death (1993) and The Ghosts Of N-Space (1996), and later appearing in a number of Sarah Jane solo stories released on CD by Big Finish Productions from 2002.

The events which led to Sladen's return to prominence amongst the average television viewer, however, began in 2005. Russell T Davies, executive producer of the new Doctor Who series, was eager to bring back a companion from the original programme in an episode which would shed greater depth to the role and fate of the Doctor's companions. Davies convinced an initially reluctant Sladen to appear as Sarah Jane, and the resulting adventure, School Reunion, proved tremendously popular with the Doctor Who production team.

Meanwhile, in the wake of the enormous success of the new Doctor Who series' first season, Children's BBC had approached Davies about developing a spin-off which would feature the Doctor as a teenager. Davies felt that this would go too far in defusing the enigma of the Doctor, however, and around the end of the year recommended instead that a new series be created to showcase Sarah Jane. This marked a return to children's television for Davies, who had originally gained notice with the youth-oriented fantasy serials Dark Season and Century Falls.

When subsequently contacted by the production office, Sladen assumed that she was being invited to appear in the adult-targetted Doctor Who spin-off series Torchwood. She was surprised by the offer to star in her own show, but ultimately agreed to come aboard the project. Finally, on September 14th, 2006, it was announced that Sladen would indeed be reprising the role of Sarah Jane in a series which would form part of the CBBC line-up. The title was initially reported to be Sarah Jane Investigates and later finalised as The Sarah Jane Adventures. It was decided that the programme would, at least initially, comprise ten half-hour episodes to air in late 2007, preceded at Christmastime by a one-hour special to establish Sarah's new status quo.

One significant change from Sarah Jane's original Doctor Who spin-off, however, was that this time, K-9 would not be available to headline the show. The character's cocreator and rights holder, Bob Baker, had for several years been attempting to instigate production on an animated programme starring the robot dog, and was continuing to pursue this project with Park Entertainment and Jetix Europe. Nonetheless, Baker did give his permission for K-9 to make a cameo appearance in the pilot episode of The Sarah Jane Adventures, explaining his absence from the ongoing programme.

The writing chores on the introductory installment were shared between Davies and Gareth Roberts. Roberts had scribed the interactive Doctor Who game Attack Of The Graske and contributed the prequel TARDISodes for that show's 2006 season; he was also writing The Shakespeare Code for transmission the next year. In addition, Roberts had contributed to series such as Emmerdale, Brookside and the revival of Randall & Hopkirk (Deceased). Long before the new series began, Roberts had become well-known to Doctor Who fans, having published a plethora of Doctor Who novels, beginning with The Highest Science in 1992 (and more recently including the Ninth Doctor tome Only Human and the Tenth Doctor “Quick Reads” release I Am A Dalek). Roberts had also cowritten two audio plays, The One Doctor and Bang-Bang-A-Boom, for Big Finish Productions, and had contributed comic strips to Doctor Who Magazine.

Joining Sladen as stars of The Sarah Jane Adventures were several young actors. Chief amongst these was Yasmin Paige, playing Maria Jackson. Paige's prior credits included episodes of Keen Eddie, Doctors and The Last Detective. Tommy Knight was cast as Luke; he had appeared in shows such as The Bill, Doctors and Casualty. Coming to the series with a more unusual background was Porsha Lawrence-Mavour. A finalist in the inaugural children's edition of the reality competition Stars In Their Eyes in 2002, Lawrence-Mavour was chosen to play Kelsey.

As with Doctor Who and Torchwood, Davies and Julie Gardner, the BBC's Head of Drama Commissioning, acted as executive producers of The Sarah Jane Adventures, and were now joined in that capacity by Doctor Who producer Phil Collinson. Selected to produce the full series was Matthew Bouch, who coproduced The Legend Of The Tamworth Two and had also earned script editing credits on programmes such as EastEnders and Holby City. However, for the debut special, the producer's chair would be filled by Susie Liggat. Liggat had mostly worked as an assistant director, on shows including Casanova, Teachers and Doctor Who (on Love & Monsters and Army Of Ghosts / Doomsday). Liggat had also been chosen to temporarily replace Collinson as producer on Doctor Who for one recording block during the 2007 season.

Davies' and Roberts' script became known as Invasion Of The Bane. For the name of Bubbleshock, Roberts drew on a beverage called “bubbleshake” he had invented for The Highest Science. As noted by Sarah in dialogue, Mrs Wormwood was named for a star (possibly a comet) described in the Bible's Book Of Revelation which falls to Earth during the End Times and poisons the world's freshwater rivers and springs; the name “Wormwood” is a metaphor for “bitterness”.

Invasion Of The Bane was filmed during October 2006. The director was Colin Teague, who had most recently helmed the Torchwood episodes Ghost Machine and Greeks Bearing Gifts. As with Doctor Who and Torchwood, the production was based in Cardiff, with studio recording taking place in the franchise's Upper Boat studios near Pontypridd.

The Sarah Jane Adventures debuted on New Year's Day 2007.

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