Mystery Tales was one of many titles Atlas hurried to the stands in the wake of the success of EC’s “New Trend” horror comics of the early 50s. Early issues featured Atlas’s typical heavy-handed mix of gory and gruesome fare, rendered by a roster of talent including Matt Fox, a young Gene Colan, Bill Everett, and the great Joe Maneely. The arrival of the Comics Code banished the buckets of blood, and the focus shifted to tales of suspense and (like the title says) mystery. By 1957, Atlas had hit the skids and cut back on all but a few titles. Mystery Tales did not survive the implosion, though stories from its pages have occasionally been reprinted in Marvel horror titles from the 70s such as Dead of Night and Supernatural Tales.
