Cold Fusion was the only multi-Doctor story involving televised Doctors ever told by Virgin Books. It involved the unusual pairing of the season 19 Fifth Doctor with the Seventh Doctor near the end of the Virgin New Adventures line.
Originally intended to be published alongside NA: So Vile a Sin to emotionally leverage Roz Forrester's death in that book, delays on Sin meant that people who read the book on publication didn't see this intended aspect of the book.
As a multi-Doctor story, its perspective was unusual. The Seventh Doctor was portrayed as largely disdainful of his earlier self's presence because of the dangers it presented. Though temporal paradoxes and other consequences of two Doctors meeting were touched upon in televised multi-Doctor stories, here they were more central. Moreover, the structure broke with the format of televised multi-Doctor stories, which held that the latest incarnation was the "current" Doctor and therefore the effective headlining "star" of the show. On balance, Fusion was a Fifth Doctor novel that happened to feature the Seventh, rather than a Seventh Doctor novel that used the Fifth.
- "The entire universe is at stake and I'm locked in here with another incarnation of myself, and not even one of the good ones!"
More than one TARDIS lands on a barren ice world. The Fifth Doctor, Adric, Nyssa and Tegan find a once ordered society on the verge of collapse, as rebels wage a dirty war with Scientifica, the ruling elite. All that stands between order and anarchy is the massed presence of an Adjudicator peacekeeping force.
But is peace the only reason for the Adjudicator garrison? What exactly has been discovered deep below the planet's surface? Who are the mysterious Ferutu? And why is telling a ghost story a criminal offence?
The Fifth Doctor sides with the cause of justice and fairness as always. But, as a threat to the universe unfolds, he finds himself in conflict with his past... and his future.
to be added
- Fifth Doctor
- Seventh Doctor
- Tegan Jovanka
- Chris Cwej
- Roz Forrester
- Adjudicator Provost-General Tertullian Medford
- Ziyou Wanle
- SAM drone
- Chief Scientist Whitfield
- Adjudicator Dareau
- Tegan has seen Blake's 7 and can cope with the idea of transmats.
- The Train Computer's statement "The lever you have pulled – “Brakes” – is not in service. Please make a note of it" is a reference to an episode of The Simpsons called "Marge Vs. The Monorail", where Homer's attempts to brake an out-of-control monorail are met with the same response.
- The Fifth Doctor is only just getting over his recent regeneration.
- The Seventh Doctor has to hide his emotions upon seeing Adric again.
- Adric has only known the Doctor for "a few weeks"
- Chris Cwej uses the alias Bruce Jovanka.
- Roz Forrester is beginning to feel her age.
- Adjudicator Provost-General Tertullian Medford is a secret member of Unitatus.
- Patience was in the house of Blyledge on "Glorious Gallifrey". She has/had thirteen grandchildren.
- Patience's husband was one of the first to explore the vortex.
- The Other's/Doctor's children were culled, but Susan Foreman was saved.
- The Fifth Doctor never uses expletives.
- The colony has a Skybase in orbit.
- The Ferutu are beings from an alternate universe in which Gallifrey was destroyed shortly after Omega's experiments; they have assumed the role of the Time Lords, and actively engage in protecting and shaping the universe. Their "technology" (if it can be called that) is more akin to magic runes.
- The Embodiment of Gris is mentioned by the Fifth Doctor.
- The Fifth and Seventh Doctors use a technique which they describe as being "beyond the science of the Humanian Era", namely reversing the polarity of the neutron flow to disarm several fusion bombs.
- A SAM drone is a mass-produced drone.
- This is the only instalment of the Virgin Missing Adventures in which the Seventh Doctor appears.
- The reasons that the Doctor seems to not remember meeting his past self in other multi-Doctor stories is discussed. In most of the televised adventures, it is credited to the Blinovitch Limitation Effect.
- "Lightspeed overdrive" is first mentioned in DW: Logopolis.
- PDA: The Infinity Doctors reveals who Patience is.
- NA: Cat's Cradle: Time's Crucible and NA: Lungbarrow both gave some idea of the time from which Patience is from.
- This story begins a series of story arcs known as the "Psi Powers" arc for the Seventh Doctor, continuing in NA: The Death of Art and ending in NA: Sleepy.
- The Fifth Doctor is still recovering from the effects of his recent regeneration. (DW: Castrovalva)
- Adric has only known the Doctor for several weeks having first met the Doctor in DW: Full Circle.
- The Seventh Doctor remembers the events of the novel from the perspective of the Fifth Doctor and uses this knowledge against his younger self. As occurs in CC: Peri and the Piscon Paradox, BFA: The Four Doctors and DW: Time Crash in which the Sixth, Eighth and Tenth Doctors respectively likewise remember the events portrayed from the point of view of their fifth incarnation.
- The Seventh Doctor describes his fifth incarnation as being "bland" and "not even one of the good ones." This reflects the Sixth Doctor's low opinion of his immediate predecessor immediately after his regeneration. (DW: The Twin Dilemma) Conversely, by the time of his tenth incarnation, the Doctor expressed a fondness for his time as the Fifth Doctor. He looked upon his fifth incarnation as a turning point in his life. According to the Tenth Doctor, it was during his fifth incarnation he truly began to enjoy himself. (DW: Time Crash)
- The Fifth and Seventh Doctors would later meet each other again in BFA: The Sirens of Time and prior to the events of BFA: The Veiled Leopard.
For the Fifth Doctor
For the Seventh Doctor
- Cold Fusion takes place after NA: Return of the Living Dad
- Cold Fusion takes place before ST: The Nuclear Option