Expiry Dating (audio story)

 was the first story in the audio anthology The Tenth Doctor and River Song, produced by Big Finish Productions. It was written by James Goss and featured David Tennant as the Tenth Doctor and Alex Kingston as River Song.

Publisher's summary
The first time the Doctor met River Song, he saw her die. And now she's asking him on a date. Well, not a date, exactly... More of a mission.

But the Doctor isn't at anyone's beck and call. Or so he thinks. With billions of lives hanging in the balance, can the Doctor afford not to do whatever River wants? Whichever one of him she asks?

Plot
Amidst in space, the Tenth Doctor stumbles across a space bottle, containing a message written on psychic paper. It's from River Song, giving him an appointment at the Apocalypse Vault, inside the Quantum Vatican. Knowing that that is the location of a fixed point in time (one day the Vatican will open the Crypt, read the date of the end of the universe and proceed accordingly) the Doctor refuses the invitation, and instead tracks down the provenance of the paper, in order to find River.

Thus begins an adventurous chase between the two of them: every time the Doctor reaches a place from where River sent a message, he finds another letter from her to him - and also a dangerous situation for him to sort out, involving tyrants to depose, wars to end and many other occurrences. And through all of this, River insists for him to come to the Quantum Vatican and reach her. Eventually, the Doctor partially relents, and goes to the Quantum Vatican - where he finds, behind a fresco recently restored, a forged copy of the Scroll of the Last Days, the paper the Vatican keeps sealed into the Crypt, and which it is supposed to reveal the date of the end of the Universe.

River finally agrees to talk about her intentions, and leaves the Doctor a message for a new date: at the Cafe du Paris, year 2160. However, the message gets picked up by mistake from the Fifth Doctor, who goes on to reach her a year later. After an initial disappointment, River decides to take advantage of the situation and starts a correspondence with him too. The Fifth Doctor grows more and more enamoured of her, and eventually agrees to steal something from her.

When the Tenth Doctor finally picks up River's message and goes to the date, the Fifth Doctor bumps into him and steals the forged Scroll. After being blamed by the Doctor for what he thinks it's a scam (River, he supposes, wants to steal the Scroll and sell back the forged one to the Vatican), the Doctor agrees to give her the Scroll, but discovers it's missing. He eventually leaves, allowing the Fifth Doctor to come out of hiding and give River back what she wanted. After that, River drugs him and admits him to have manipulated him, using a substance to make him more suggestionable and then giving him something to make him forget what happened.

Some time later, the Tenth Doctor once again writes to River. He's angry, because he just found a message from the First Doctor to River and a voice mail from the Sixth Doctor; both of them tell her not to bother them anymore with their request to join her at the Apocalypse Vault. Thinking that she would just send a message to any random incarnation of him because she intends to use him to break into the Crypt, the Tenth Doctor angrily tells her not to call him anymore, and refuses to reach her at the Cafe from one more date. River replies and assures him she never meant to just use him, that he matters very much to her, and insisting about them meeting at the Cafe for one last date.

The Tenth Doctor agrees and reaches her, only to end up being shooting at by armed mercenaries at the service of the Vatican, who blame him for the theft of the Scroll. Determined to end this story, the Doctor agrees to meet River at the Vault. When she arrives, though, she only finds a message for her. The Doctor had come to the Vault, broke into it and got out the original Scroll, leaving it here for River to make her choice and show him who she really is. If she will steal the Scroll, then she will prove herself to be just a thief; if she puts her back, she will show to have some honour and dignity.

Later, River replies to the Doctor through an hologram she left in the TARDIS. She says she never wanted him to steal the Crypt, she just needed the TARDIS to go back in time and place her forged Scroll in the original's place, just at the moment the Crypt was being built; she also added two more zeros to the date of the end of the universe. In this way, when the Vatican will open the tomb (this is the fixed point, and this will not change), they'll believe the God allowed the universe more time, and will not proceed to end it for some time. River also adds she designed all this plan to comfort the Doctor of the recent loss of Donna Noble, leading him from planet to planet and make him save all of those worlds, showing how he could still be useful and do good. She also assures him that one day he will know who she is. Moved and proud, the Doctor thanks her, before going on with his life.

Cast

 * The Doctor - David Tennant
 * River Song - Alex Kingston
 * The Fifth Doctor - Peter Davison
 * The Sixth Doctor - Colin Baker
 * Borslav / Bird King / Maxim / Assassin - Glen McCready

Continuity

 * The Sixth Doctor is travelling with Melanie Bush, who is from the 1980s. (PROSE: Business Unusual, TV: Terror of the Vervoids et al)
 * The Fifth Doctor receives River's message via his Space-time telegraph. (TV: Revenge of the Cybermen et al)
 * The Fifth Doctor is travelling with Tegan and Turlough, and they go to the Eye of Orion. (TV: The Five Doctors)
 * The Tenth Doctor vaguely recognises the Fifth Doctor in the brief glance he gets from bumping into him. (TV: Time Crash)
 * Unless she is faking it, River Song seems not to recognize the Fifth Doctor when he shows up at the Café, placing this story before AUDIO: The Lady in the Lake or before she collects photos of every incarnation as shown in TV: The Husbands of River Song.
 * River Song is aware of Donna Noble's fate. (TV: Silence in the Library)
 * The Doctor's last meeting with Davros is fresh in his mind. (TV: The Stolen Earth/Journey's End)
 * River Song uses a perception filter. (GAME: The Eternity Clock)
 * The Tenth Doctor reverse the polarity (TV: The Sea Devils et al.) trying to overcome River Song.
 * River Song travels on the Orient Express. (TV: Mummy on the Orient Express)
 * The Doctor mentions Romana's taste in fashion. (TV: The Ribos Operation)
 * The Doctor uses Charged Vacuum Emboitement spillage to track down the source of one of River's messages. (TV: Full Circle)