We see some of Oscar's time before leaving Honduras, and we return to the present where he and Liddy narrowly escape drowning in some kind of containment tube. They land in an artificial biome, and things seem to be taking a turn for the better—until they make a few more horrific discoveries.
Barrier #4 gives us some background on Oscar, as you likely intuited from that summary. We learn some of what he dealt with in Honduras and, if you can pick up on some of the Spanish, why he left. Even without knowing Spanish, it is impressive that the scripting, sequencing, and art can convey as much as they do for the reader.
Those "horrific discoveries" mentioned above are impressively shocking, once more thanks to the sequencing and art of Marcos Martin and Muntsa Vicente. They also deliver some gut-wrenching character moments between Liddy and Oscar, culminating in a bit of a "hell yeah" moment when they finally learn how to work together.
There is a lot to be said of the art in this comic. A section in the middle shows us the aliens and their language, which is represented only by different colored text boxes. That's a clever visual plot reminiscent of the alien language in Close Encounters of the Third Kind which adds to the theme of language barriers. The design of the aliens is wonderful and bizarre, and the world in which Oscar and Liddy now struggle is gorgeous. The detailing is impeccable, and the color art is wildly contrasting and add a lot of life to each panel.
Barrier #4 is a faster-moving issue than the previous installment, and it delivers more engaging character drama while showing the ingenuity of our leads. The art continues to astonish in its creativity and beauty, and this series earns itself another strong recommendation. Give it a read.