Writer/artist John Byrne's retro take on the X-Men, set between their Silver Age title and the All-New, All-Different incarnation, comes to a calamitous conclusion. The original X-Men take on the Brotherhood of Evil Mutants, mutant-controlled Sentinels, Angel's evil uncle Burt, the long-lost Yeti, Kraven the Hunter and the mysterious mutant group the Promise and a 'crossover' with a classic Lee/Kirby/Romita Fantastic Four tale. Collecting: X-Men: The Hidden Years 13-22, Fantastic Four (1961) 102-104; material from Yellow Claw 2 and Amazing Adult Fantasy 14.