Join Thor and his family on a titanic tour of the Ten Realms! Witness the ancient origin of Yggdrasil the World-Tree! Thor leads a desperate battle against the relentless Mangog - for Asgard! Learn how a foolhardy adventure in Niffleheim led young Thor to be banished! Loki declares war on Midgard - and visits his childhood self in Jotunheim! From Svartalfheim, Dark Elf Malekith plots to unleash the Casket of Ancient Winters - and Odin recalls the ancient trip to Muspelheim that began his age-old rivalry with Surtur! Plus: Alfheim! Vanaheim! Nidavellir's role in the origin of Mjolnir! And the stunning revelation of the Tenth Realm of Heven! Collecting THOR (1966) #157, #159, #233-234 and #347-349; THOR (2007) #12; THOR: THE TRIAL OF THOR; MIGHTY THOR (2015) #12; ORIGINAL SIN #5.1; and material from JOURNEY INTO MYSTERY (1952) #97 and THOR (1966) #400.