There are four of them. They are special forces soldiers. They are called "sea devils", although by right they can be considered knights of the three elements: they act on land, in water and in the air. Each of them has his own character and his own destiny, but each is determined to fulfill his professional duty, regardless of the risk. The concepts of "brotherhood", "friendship", "officer honor" are not just an abstraction for them, but something that they value and for which they are ready to sacrifice their lives.