Wikipedia
After Superman's death and to protect the US from future metahuman threat,
Amanda Waller forms Task Force X, a task force of six incarcerated
supervillains coerced into working for the government by implanting them with
nanite bombs. Waller already has a hold on Enchantress, a sorceress who
possesses the body of archaeologist June Moone, by physically controlling the
heart of the sorceress. Enchantress however manages to escape Waller's
control, conquer Midway City and summon her brother Incubus to destroy
humanity. Task Force X is joined by Rick Flag who is in love with Moone, and
his associate Katana. Their first target is to extract Waller from her HQ in
the middle of Midway City and cover up her involvement with Enchantress.
Meanwhile Joker, lover of Task Force X member Harley Quinn, tries to free her
from her nanite bomb, but is eventually believed to be dead. The squad then
abandons Flag until he relieves them of their mission, and they then decide to
prove themselves by saving the city. While some of the squad kill Incubus,
Harley Quinn tricks the Enchantress into believing she wants to join her,
takes her heart from her chest and destroys it, releasing Moone from her
control. Waller sends the squad back to their cells with reduced sentences,
but Joker comes back and frees Harley Quinn.