Reportedly the one where Archer meets an attractive woman that turns out to be a changling from the future on a mession to try to sabatoshe Enterprises mission.
Something goes awry and in one scene there are two Porthoses and Archer is pointing his phase pistol at them, trying to figure out which one is the real one.
Also contains the scene where they get a message from Starfleet HQ and as their speaking to Admiral Forrest, a sliding vortex openes behind him and out flies, er well I don't wana spoil it.