WARNING!!! THIS NEXT ACT CONTAINS EXPLICIT SEXUAL MATERIAL!
IF YOU WISH TO SKIP THIS THEN I WILL GIVE A SHORT RUNDOWN ON THE IMPORTANT THINGS THAT HAPPEN BELOW.
Basically Shirou wakes up, completely paralyzed by the aftereffects of the toxins that were implanted in Shirou's body via the needles Nanaya Takeshi stuck within his nerves to cut his prana flow to Saber. Rin examines him and explains that he's constantly leaking prana, and if his nerves aren't repaired he'll run out completely and then die.
She takes it upon herself to instruct Saber and for some reason Sakura (Who is already the Queen of Ero anyway.) on the proper "ritual technique" required to mend Shirou. Rin and Saber leave the room leaving Sakura to start Shirou's engine, (wink wink, nudge nudge). The three of them exchange their "mana/prana" with him and Shirou is healed.
And that pretty much sets you up for the next ACT.