One of the weird, tiny details in Star Wars: The Force Awakens was C-3PO’s arm. The once entirely golden droid now featured a red left arm. Its presence was never explained in the film, leaving the most diehard among fans wondering about why it was there at all.

Now we know what’s up. The story behind the red arm was revealed in the first issue of what’s going to be, I assume, a limited run in Marvel’s Star Wars comics line. It comes from Star Wars: C-3PO #1, by James Robinson, Tony Harris, and Joe Caramagna.

Spoilers ahead: While I won’t be posting whole comic pages for you to pore over, I will toss up a frame and spill the big plot details quickly. If you want the whole story, buy the comic. Comics are cool.

C-3PO loses arm in comic

In the issue, C-3PO and a group of Resistance droids meet and capture a philosophical droid named Omri (weird already, right?).  Some violence goes down, and Omri winds up sacrificing himself to save Threepio. The golden droid we all love is the only one to make it away from the struggle.

Basically, in a moment of self-sacrifice, Omri helps Threepio by walking out into an acid rain storm. The storm eats away his paint and metallic parts, Omri loses his arm (now revealed to be red) and “dies.”

Threepio makes Omri’s arm his own in order to honor the sacrifice the droid made.

Crazy, right? I’ll take this story, for sure. Now, here I go to buy the comic…