SPOILER WARNING: The following review discusses events in "The Unworthy Thor" #4, on sale now.

What does it take to be worthy? In “Unworthy Thor #4,” writer Jason Aaron reveals the emotional price and perspective required for worthiness.

The Collector has taken possession of Old Asgard, the resting place of Ultimate Thor’s hammer. Odinson and Beta Ray Bill escaped The Collector’s prison last issue and with the help of a Hel-hound they freed are fighting their way to the hammer. But Thanos sent Black Swan and Proxima Midnight to retrieve it, and they are already engaging The Collector’s forces when Odinson and his friends join the fray. The issue would have been entertaining enough if it was just one huge battle, but the day is finally here where we learn what it takes to be worthy.

Three gorgeous flashbacks tell the story of Thor’s long struggle to be worthy of Mjolnir and to remain so. Each flashback utilizes a different artist, making it very clear that the story has been removed from the Odinson’s present fight that was rendered beautifully by Olivier Coipel and Kim Jacinto.

The first flashback is to a young and impatient Thor, who believes that his mighty deeds should have earned him the hammer by now. Jason Aaron delivers a fascinating conversation between Thor and Freyja in which Thor reveals that the hammer calls to him. This is an interesting tie-in to the current run of Mighty Thor in which the hammer also speaks to Jane Foster. Frazer Irving’s brooding art captures Thor’s frustrations and his earnest desire to be worthy as Freyja wisely counsels her son that, “No hammer in all the heavens can make you a better god. Only the heart that beats in your chest can do that.”

Sexy and thoughtful, Esad Ribic’s second flashback is an intimate conversation between a worthy Thor at the height of his powers and his lover, a cancer-free and vibrant Jane Foster. Thor contemplates his worthiness as he studies the hammer in the early morning light and reveals to Jane that each day he doesn’t know whether or not he’ll be able to lift the hammer, until he does, “Worthiness is not an absolute condition. It is something for which even a god must never stop striving.”

It’s in the word “striving” that Aaron gives us the final clue as to how much longer we’ll have to wait for Thor to put all the pieces together and reclaim his status as worthy — not long at all.

Russell Dauterman gives us the final flashback, a chilling one-sided conversation between a newly unworthy Thor and a cancer suffering pre-Thor Jane Foster. His self-pity blinding him to the woman who, despite all her own troubles, loves him and believes in him still, Dauterman’s Thor is perfectly lost. This is the scene that breaks your heart.

“Unworthy Thor #4” isn’t the issue where we get the big payoff that will likely conclude this excellent series. This is the issue where we learn that worthiness is an emotional state, a persistent life perspective, and a condition that requires constant striving. Odinson is almost there.