Comic & e-Comic Book
Published April 2016 as C-3PO #1 by Marvel:

Issue #1

Hardback Graphic Novel
This story is included in:

Shattered Empire

Synopsis:
While transporting 0-MR1 (Omri), a First Order droid who may know the location of captured Admiral Gial Ackbar, a group of droids, C-3PO, CO-34, PZ-99, VL-44, and Toomedtoo, crash land on the desolate planet Taul. With their transport ship's communications damaged, the droids seek a way off the planet and decide to try to make their way to a crashed First Order TIE fighter in the hope that the starfighter's comm unit is still functional. While they discuss amongst themselves existential questions of their own existence, they soon find themselves facing a series of natural hazards that they must overcome. During several encounters their numbers begin to dwindle and in one encounter with a fierce creature C-3PO loses an arm. By the time they get close to the crashed TIE fighter only Threepio and Omri remain. But in order to reach the starfighter the droids will have to expose themselves to deadly acid rain and choosing friendship over programmed alliengence, Omri gives Threepio Admiral Ackbar's location before setting out into the rain by himself. Though he successfully reaches the TIE fighter and transmits a distress signal to the Resistance, it was while trying to return to Threepio that Omri falls apart as he succumbs to the effects of the acid rain. When Poe Dameron and BB-8 arrive they find C-3PO holding one of 0-MR1's arms, now scoured red by the effects of acidic damage, and mourning 0-MR1's self-sacrifice. The golden droid pledges that he will use the red arm as a memorial to the sacrifices of Omri and the other droids.

Related Stories (in chronological order):

• A New Hope
• The Empire Strikes Back
• Return of the Jedi
• C-3PO: The Phantom House
• The Force Awakens