Still On Patrol

In the year 1989, the SSBN Asphodel disappeared without a trace. One second it was there -- the next, it was gone. Of course there were searches, inquiries, accusations... but those naturally tapered off as it became evident that the missing sub would never reappear. Until it did, two hundred and forty-three years later. Where had it been for over two centuries? Why did it reappear? And what caused it to disappear in the first place? Irwin-class MAID 644G6 has come from the far future to find the answers to these mysteries. Will she succeed? Or will she only turn up more questions?