The Key of Vaga was the fifth story in the Doctor Who Annual 1982. It was the first short story to feature the Fifth Doctor. It takes places in an unidentified gap when the Doctor travels only with Adric. It recognised that the Doctor can build inter-dimensional craft.
The Planet Vaga faces its darkest hour. The only hope for its people lies with a boy called Adric and his friend, the Doctor...
The TARDIS lands on Vaga and the Doctor has to hurry to delay the landing of an inter-dimensional craft possessed by Vagans. He does so, but then a Pyron space-shark arrives and begins bombarding them. While Adric creates a distraction, the Doctor runs for the TARDIS.
The Vagan craft arrives and uses a beta-force field to prematurely detonate the Pyron ship's warheads, destroying it. Valtar, a Vagan the Doctor met on a previous visit, appears to the Doctor and Adric.
- The modular transmission linkage is a TARDIS component that allows the Doctor to know when he's landed.
- The Pyrons destroyed Vaga's larger sun when they fired a plinium missile into it. The Vagans population was dead within one Vagan year.
- The Doctor helped design the Key of Vaga.
- Pyrons use a craft called a space-shark. It is equipped with both plinium and zargon missiles.
- The unidentified gap in which the Fifth Doctor travels only with Adric would appear to be at some point between Castrovalva and Four to Doomsday, bearing in mind the tight continuity between other stories in season 19, while Nyssa and Tegan are presumably having a break from the TARDIS.
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