This song is especially poignant this year.
The song comes from Yitzy Bald's first NYBC album. The lyrics are from a Kinnah we say near the end of Kinnos, "צִיּוֹן, הֲלֹא תִשְׁאֲלִי לִשְׁלוֹם אֲסִירַיִךְ" - Tzion, how is it that you don't ask about the welfare of your captives?!
This song starts with words from the middle of the kinnah: "וְעֵת אֶחֱלֹם שִׁיבַת שְׁבוּתֵך" - and when I dream, I dream of the return of your captives. What a stirring Kinnah for this year.
The background of this kinnah is also really somber. As I saw in the Artscroll Kinnos, this Kinnah was written by Rav Yehuda Halevi, the Kuzari. He yearned his whole life for Yerushalayim - he penned the words "Libi Bamizrach Va'anochi Besof Maariv." Finally, he undertook the journey to the Holy Land. As he passed Damascus, he stood facing Yerushalayim and he composed the above Kinnah. When he finally reached the Holy Land, he knelt down to kiss the ground, and he was trampled to death by an Arab horseman.