The Haftarah of Tzav is only read on leap years, and only if it is not also Shabbat Zachor. Otherwise, Tzav usually falls out on Shabbat HaGadol
It is from Yirmeyahu, and it is not good news.
Linear annotated translation of the Haftarah of Tzav
For an explanation of the ironically straight-forward connection, and an additional connection to Purim, see Forms of Worship