The Keeper was the 12th and final episode of the third season of The Sparticle Mystery, as well as being the final episode to the programme as a whole. It was broadcast at 5pm on 23 March 2015 on CBBC and CBBC HD.
The Sparticles arrive at the location of the Seventh Sensitive, believed to be an old lighthouse keeper. Meanwhile, Kylie and her minions arrive at the lighthouse as well to execute her plan. Holly gives birth to Kimmy at the end of the episode.
- Sadiq says that the Keeper is the last adult on Earth. This contradicts season 1 which featured an adult, called Anita, who was trapped in the world of children when the worlds separated. (She may have perished after season 1, given how poor her health was.)