Spoilers for John Walker: The U.S.Agent #5 ahead!

The USAgent, John Walker’s, true nemesis has been revealed; his own sister! Though she wasn't featured in the MCU's The Falcon and The Winter Soldier, John Walker's sister has played an important role in the comics, and her shocking plan was just revealed in a new comic.

Created by writer Mark Gruenwald and artist Paul Neary, John Walker has had several different identities over the years. For a brief time, John Walker replaced Steve Rogers as Captain America after the Red Skull manipulated public opinion against him. Unlike Rogers, John Walker was much more nationalistic and rigid in his thinking, and ultimately proved unstable and not worthy of calling himself Captain America. He then became the USAgent, an identity he has held ever since. Recently, Walker learned he had been replaced as the USAgent by a new person named April Manning, a woman with ties to the USAgent’s sister Kate. Much like her brother, Kate wants to help America, and free it from those who would try to destroy it, but her plan to solve it involves destruction and murder. Specifically, Kate wants to resurrect the American Kaiju program, a failed attempt at duplicating the Super Solider Serum.

Related: The MCU Gives John Walker Steve Rogers' Nomad Story 

Now, John Walker: The U.S.Agent #5 from writer Christopher Priest, artist Georges Jeanty, inker Karl Story, colorist Matt Milla, and letterer Joe Sabino, sees USAgent make his final stand against his replacement. As the two fight, USAgent swears he will make April Manning pay for what he has done to his sister, but then Manning drops a bombshell on him: the whole plan was Kate’s idea. Her ultra-patriotic mode of thinking has become even more warped and distorted than her brother’s, and now innocents will pay the price. However, one of the kaiju she has unleashed crashes into her heli-carrier, and in the confusion. Manning shoots Kate, killing her as the heli-carrier crashes to the ground.  USAgent is then able to defeat Manning and take back his title.

The USAgent and his sister are two peas from the same pod—both are committed to the concepts of duty and country, and both have taken this philosophy to its extreme. The main difference between the two is the USAgent has tempered his views over the years whereas his sister has not, and has become even more extremist in her thinking. Her death serves as a reminder to the USAgent what can happen when ideals become corrupted and twisted.

The USAgent has faced many threats to America, and in John Walker: USAgent #5, he faces one of the most diabolical yet: his own sister. She sought to replace her brother, but in the end, fell victim to her own poisoned ideology.

Next: Making John Walker An Antihero Ruins His Story