The fifth angel blows his trumpet and a star falls to earth, where it is given a key to the bottomless pit (v. 1). He (or maybe she? It's quite hard to identify a star's gender) turns the key in the lock and opens the door, which emits a giant belch of smoke that blocks out the sun and moon. Locusts fly out of the smoke and are given the power of scorpions. They're told to leave the grass and trees alone and to focus their rage solely on the humans who don't have god's seal of approval on their foreheads. They're also instructed not to kill the non-marked people, just to torture them with scorpion stings for five months. They're promised that the men will want to die, but won't be able to. John gets a closer look at the locust/scorpions, and sees that they look like battle horses wearing crowns and with the faces of men, hair of women, lion's teeth and scorpion stingers. They're wearing breastplates and their wings sound like chariots.
The locusts have a king, Abaddon on Hebrew or Apollyon in Greek, or 'The Destroyer' in English, because this book can never, ever be subtle.
The sixth angel sounds and one of the horns on the altar starts speaking. It tells the angel to let four other angels who are currently imprisoned in the Euphrates river out. The angels have a year, a month, a day and an hour to kill a third of the people on earth, so clearly they need an army of 200 000 horsemen, mounted on horses wearing breastplates of fire, and of jacinth, and brimstone (v. 17) and with the heads of lions that breathe fire, smoke and brimstone and bitey snakes for tails. With all this in place, they run around and kill a third of the populace. The non-believers who don't die also refuse to repent.
Yet another angel flies in, this one wearing cloud clothing and a rainbow hat. His face is as bright as the sun and his feet are pillars of fire. He lands with one foot in the sea and the other on land. He's holding a little book. He opens his mouth to speak and roars like a lion. When he stops, John goes to write what he said down, but only gets as far as raise show dogs before the angel tells him to keep what he said a secret. Then he raises his hands to heaven and swears that time stops now. He also says that when the seventh angel blows his trumpet, it will be the fulfillment of god's plan. God then speaks and tells John to go take the book from the angel. He does, and the angel instructs him to eat it, but promises it will taste like honey but eventually give him a tummy-ache, because paper is indigestible.