The Split Infinitive (audio story)

 was the second story in the audio anthology The Legacy of Time, produced by Big Finish Productions. It was written by John Dorney and featured Sylvester McCoy as the Seventh Doctor and Sophie Aldred as Ace.

Publisher's summary
A criminal gang appears to have recruited a member with time-bending powers. It’s a case for the Counter-Measures team – in the 1960s and the 1970s! The Seventh Doctor and Ace have their work cut out to save the day twice over, and make sure Gilmore, Rachel and Allison don’t collide with their past, or their future.

Plot
1970s. The Counter-Measures team gathers to investigate a series of strange robberies to heavily armed places, which seemingly present not only no trace of robbery, but also no bodies. The robberies are suspected to be the work of a new gangster, Kazan, whose name seems oddly familiar to the team. But it is only when they spot the Doctor in one of the pictures of the case they start to remember.

1960s. The Counter-Measures team gathers to investigate a series of strange murders; the victims seem to have been mysteriously aged to death; The robberies are suspected to be the work of a new gangster, Kazan. Their meeting is interrupted by Ace, who suddenly drops in saying that the Doctor sent her. Ten years later, the new meeting of the team is also interrupted by the Doctor barging in unannounced, saying that he comes for help.

In their separate times, the Doctor and Ace explain that the TARDIS detected a powerful time distortion, which is currently drawing towards one another the two decades and threaten to cause a black hole. The Doctor sent Ace to the 1960s so that she could track down the source of the distortion in that time period, while he himself would do the same thing in the 1970s; since the Counter-Measures team operated in both, their shared memories will help the Doctor to keep track of Ace's progress.

In the 1960s, thanks to a tracking device given her by the Doctor, Ace and the Counter-Measures storm across Kazan and his men robbing a bank; in the following fight, a shimmering figure he calls "Puncheon", which works for Kazan, touches some men and ages them to death, thus revealing himself as the source of the murders. He also touches Ace, but since she is a time traveller, it doesn't affect her. The thieves manage to escape, but the tracking device once again reveals their hideout: Fortress Island.

In the 1970s, the same tracking device leads the Doctor and the team to Kazan's penthouse. Thanks to Ian Gilmore's memories, the Doctor is informed of what Ace discovered, and gathers that "Puncheon" must be the survivor of an experiment in time travel, who split him in two across time. Rachel Jensen and Allison Williams knock out the doorman of the penthouse, take hold of the security system and put Kazan and his right-hand man to sleep with gas, allowing the Doctor and Ian to enter the building and retrieve "Puncheon".

In the 1960s, Ace puts charges of Nitro-9 all around the perimeter of Fortress Island, and has Rachel and Allison detonate from afar, thus tricking Kazan and his men into thinking they are under attack; the distraction allows her and Ian to come into the fortress and take "Puncheon". The team makes his way back to the Post Office Tower via aeroplane, but they are attacked by Kazan and his men, revealing themselves as Rocket Men. Ace and Ian have Rachel and Allison jump off the plane with the two parachutes they have, while Ian tries fending off the attack, but Kazan succeeds into breaking onboard and throws Ace off, to her death.

In the 1970s too, the Rocket Men attack the Doctor and the team on their way back to the Tower, but they manage to elude them and reach the Tower. While the team stays behind to face the Rocket Men, the Doctor has Ian tell him where Ace was supposed to fall, and then takes off in the TARDIS together with "Puncheon". He saves Ace by using a gravity field to stop her falling, then materialises aboard Ian's plane and takes also the other "Puncheon" in the TARDIS.

Meanwhile, Ian has subdued Kazan and locked the controls of the plane so that it falls in a spot where there will be no casualties; determined not to leave Kazan to die, he wears his jetpack and tries getting him to safety. Kazan, however, refuses his help, and as a result falls to his death. As the two "Puncheon" touch each other, the temporal distorsion is solved, Kazan is erased from history due to his death in the 1960s and the other Rocket Men are swept off elsewhere.

There only remains the enigma of "Puncheon"'s origin, but the Doctor is sure he will found out in the future.

Cast

 * The Doctor - Sylvester McCoy
 * Ace - Sophie Aldred
 * Group Captain Ian Gilmore - Simon Williams
 * Professor Rachel Jensen - Pamela Salem
 * Doctor Allison Williams - Karen Gledhill
 * Sir Tobias Kinsella - Hugh Ross
 * Kazan - Vince Leigh
 * Vince - Glen McCready
 * Rocket Man - James Joyce

Continuity

 * It is implied that "Puncheon" is one of the members of the Time Lord crew which attempted the first test flight of a TARDIS on Henlen; his fate is the result of the Sirens of Time hijacking that same experiment and creating a paradox to feed themselves. The Seventh Doctor would later be called on by Bernice Summerfield to resolve the paradox by piloting that first TARDIS together with other incarnations of himself. (AUDIO: Collision Course)
 * For the Doctor, this is at least the fourth encounter with the Rocket Men (AUDIO: The Rocket Men, Return of the Rocket Men, Requiem for the Rocket Men) and the first in this incarnation. (AUDIO: The Two Masters)
 * The Seventh Doctor presumes that, given his repertoire defeating the likes of Daleks, he "can't imagine ordinary gangsters will offer too much opposition". The Doctor would later meet the end of this seventh life after getting shot by ordinary gangsters while exiting the TARDIS. (TV: Doctor Who)
 * The Doctor notes that the after-effects of the temporal shockwave might create inconsistent chronology for nearby time travellers, and remarks that he'd always wondered how someone could have retired in the 1970s, (TV: Mawdryn Undead) after having worked in the 1980s. (TV: The Invasion, Pyramids of Mars)
 * On meeting the Counter-Measures team in the 1960s, Ace learns that UNIT are yet to exist. (TV: The Invasion, et al.)
 * In another occasion too, a temporal distortion was solved by two versions of the Brigadier touching each other. (TV: Mawdryn Undead)