After three days of constant fighting and visions of horror, Desmond had finally managed to find some clues to Lilith's whereabouts, but what he found wasn't exactly to his liking.
At first, Desmond thought that, given how illustrious Lilith had been in her time, she should appear in all the history books. Lilith's downfall apparently was later covered up or disguised as something else. Yet, Desmond believed that, as one of the progenitors of the most powerful race in this world, it was only fitting that she would still be remembered.
One can imagine Desmond's surprise to discover that no matter how hard he tried, Lilith's name was nowhere to be found. If that were all, Desmond would still understand, given the power of those who planned Lilith's downfall; erasing the woman from history didn't seem impossible, but that wasn't all they did.