Episode 29 of The Trigan Empire
The Masked Raiders
aka Revenge of a Friend
De wraak van een vriend (Dutch title)
Revenge of a Friend (Dutch title, translated)
The Masked Raiders was originally published in 11 installments in issues 506 (25 September 1971) to 516 (4 December 1971) of Look and Learn magazine.
It is reprinted in the Don Lawrence Collection Volume 8, The Prisoner of Zerss.
Plot summary (Dutch)