Lupa's Quest:

Lupa's ancestors call upon her, but the young she-wolf is hesitant to answer. However, to live on in the light of her companion and to stay by his side, she'll take on the greatest journey known to her kin to claim her birthright and return as a new being. Max and Fluttershy await their friend, but Lupa? The Wolfmother-to-be strides toward herdestiny.

(This occurs in the middle of A Thief's Tale: the Road to Redemption from Chapters 26~34)