Just looking at the description, there may not be much to get excited about in this volume of Eureka 7. The high-flying intensity of the previous installment is a tough act to follow, and now we're stuck with a block of episodes that boils down to "Gekkōstate gets stuck in a cave." Taking a break from the action opens up new possibilities, though; suddenly the crew's got a whole lot more time to think. Maybe too much time. Young hero Renton has another one of his weird dreams, crusty old commander Holland is being even more crusty than usual, and Eureka—well, whatever's going on with Eureka is anyone's guess. This is a time to look inward and ask where the characters are headed, and the answers could be more complex than anyone might expect.

Before things get all gloomy, however, there's still time for a little comedy and action. The health craze in Episode 15 brings its share of laughs: the entire crew performing Tai Chi, a sudden shortage of junk food, and misadventures in search of the nutritious puncha nut. (If that's not a pun, I don't know what is.) Even as the episode turns towards battle, the spirit of triumph still wins out—Renton piloting the Nirvash by himself and taking out the enemy is pure exhilaration in visual form. But Episode 16 inverts everything and becomes pure introspection in visual form: Renton, lost in the cave and mentally drained, succumbs to a dream sequence that sums up his conflicted feelings for Eureka. Of course, he wants to fly and develop his skills—but is it worth Eureka getting jealous over "her" machine? The story continues to develop on multiple levels, becoming even more mysterious when Eureka "takes a nap" and somehow enters Renton's dream.

After such emotional hand-wringing, Episode 17 is a welcome relief as Renton and the crewmembers head out to meet a repairman and do some male bonding. Although repairing the Gekkōstate is the most obvious plot theme, Renton and Eureka's strained relationship is the real substance throughout this arc: the men of the ship tease Renton about his progress, while Hilda helps Eureka work out her feelings by putting it in concrete terms. Teen angst is truly universal, isn't it? The episode after that goes even further, pushing Renton into a deeper slump when he discovers that cool old guys aren't always all that cool. Confused about his world, confused about his goals, and confused about love—what these episodes lack in action, they make up for with serious character development. The only problem is that ending the disc on such a downer can feel unsatisfying for some.

No matter where the story heads, though, one can always expect strong visuals from the creative minds of Studio BONES. The climactic scenes of Episodes 15 and 16 show great versatility by way of contrast: the Nirvash maneuvering gracefully through a sunset sky—a very traditional sort of beauty—and then, one episode later, an explosion of surreal imagery in Renton's dream. Frank Lloyd Wright's Fallingwater, an attempted apology to Eureka, LFO units drifting through the ceiling—it may not match the grand scope of the Coralian incident, but this scene still holds its own as a visual experiment. But the basics of animation are also handled well: the memorable character designs are as consistent as ever, with even one-time characters having a distinctive look, while high frame rates and attention to detail keep motion and action looking smooth. A diverse color palette makes this series attractive to watch, even in the darkness of the cave, with unusual textures and surprises waiting in the ruins.

A wide-ranging music score gives Eureka 7 a feeling that's both classic and modern—rich orchestral sounds dominate dramatic scenes, but rock and dance tracks are the genres of choice when the Nirvash takes to the sky. Either way, the results are always tuneful and fitting. The same might be said of the lively opening and ending songs: Home Made Kazoku's "Shounen Heart" captures the adventurous coming-of-age spirit through hip-hop, and Asami Izawa's catchy "Fly Away" says more of the same but with a soul flavor.

The many emotional scenes in these episodes are handled confidently in the English dub, with Johnny Yong Bosch leading the way as Renton. For a character that goes through several moods in each episode, he gets all of them right, while still maintaining that youthful, high-pitched tone. Stephanie Sheh's Eureka is equally adept, although her rhythm could be more flowing. The supporting cast all turn in solid performances as well, and with a script that follows the subtitles closely (sometimes even matching word for word), this is one title that you could easily watch dubbed all the way through.

The Japanese voice cast still deserves their share of credit, though, being the main source of extras on this disc. Look forward to a full audio commentary (subtitled, of course) for Episode 15, and a 30-minute interview with Yūko Sanpei (Renton) and Kaori Nazuka (Eureka) discussing their characters and the show. Occasionally they mention episodes that haven't shown up on DVD yet, so consider that your spoiler alert—but the segment is still worth watching for their insights and humor.

Even as it winds down from the high intensity of the previous volume, Eureka 7 continues to be an engrossing series. These episodes turn to the inner world of the Gekkōstate's crew, particularly Renton and Eureka's states of mind, and pose new challenges that can't be solved by simply piloting the Nirvash. In an underground cavern, history and technology are examined. In a surreal dreamworld, true feelings are discovered. In Eureka 7, a young boy's heart still has plenty of growing up to do.