Karin Grace was a member of the original Suicide Squad. She is also a member of the second incarnation of the team, taking the role of emergency medical operator.
Not long afterwards, Karin Grace was one of the first four to join the first team of the Suicide Squad, along with Rick Flag Jr., Hugh Evans, and Jess Bright. However, working as a doctor and experienced medical operator, she grew closer with Rick Flag Jr. She grew so close, that they began a romantic relationship. However, their relationship soon ended as the squad was soon disbanded for a while.
After a long time, she joined the new squad as the medical operator, yet along with her joining the team, she meets Rick Flag Jr. once again. The debriefing is heard, when Amanda goes over the members of the Jihad and the plans for the Suicide Squad to infiltrate "Jotunheim", base of the Jihad. On boarding the plane to take them to their mission, Rick Flag encounters Karin.
Dealing with their issues, The Suicide Squad enters Quarac to defeat the Jihad, which they do successfully. True to their name, though, not all the members of the Suicide Squad survive the experience.
When guarding Glorious Godfrey at Belle Reve, which is a prison that also holds the secret headquarters of the Suicide Squad, a blast happens. The Female Furies arrive from Apokolips to Earth to return Glorious Godfrey to his home planet and face Darkseid. A battle ensues, though the Female Furies are able to kidnap Glorious Godfrey and escape.
Slipknot attempts to desert and has his arm destroyed by the explosive bracelet each Squad member wears. A hard-fought skirmish ends as the Bronze Tiger is injured and Karin Grace is abducted by a Manhunter. Leaving the Tiger behind, Flag takes charge and storms the temple to complete the mission. After Deadshot and Captain Boomerang are cut off by enemy forces, Flag and the Privateer find Karin and rescue her, and Flag is astounded to learn that Karin is herself a Manhunter agent.
As she holds him at gunpoint, she explains how, while recuperating after the final mission of the previous Suicide Squad team, she met and fell in love with Mark Shaw, who inducted her into the Manhunters. The next second, it is Karin's turn to be astonished, as the Privateer claims that he is not the Mark Shaw she knew, and quickly disarms her. Then a costumed Manhunter appears, and claims to be the real Shaw, while the Privateer is merely an android. The Manhunter then knocks Flag and the Privateer unconscious, and instructs Karin to kill them. She hesitates at the memory of her former romance with Flag, and before she can act, her Manhunter ally begins to fall apart, and is thus revealed as an android. On the temple grounds, the other Manhunters also fall apart, one by one.
Ordering Shaw to take the still-unconscious Flag to safety, Karin, now realizing how she had been duped, pilots the explosive-filled "Baby Huey" into the center of the Manhunter base, where it crashes, pinning her and the Mark Shaw android beneath it. She kills herself to finish the mission they have been given and succeeds.