John Perry did two things on his 75th birthday. First he visited his wife's grave. Then he joined the army. The good news is that humanity finally made it into interstellar space. The bad news is that planets fit to live on are scarce—and alien races willing to fight us for them are common. So: we fight. To defend Earth, and to stake our own claim to planetary real estate. Far from Earth, the war has been going on for decades: brutal, bloody, unyielding. Earth itself is a backwater.

Our universe is ruled by physics, and faster-than-light travel is not possible - until the discovery of The Flow, an extradimensional field we can access at certain points in space-time that transports us to other worlds, around other stars. Humanity flows away from Earth, into space, and in time forgets our home world and creates a new empire, the Interdependency, whose ethos requires that no one human outpost can survive without the others. It's a hedge against interstellar war - and a system of control for the rulers of the empire.

Inheriting your uncle's supervillain business is more complicated than you might think. Particularly when you discover who's running the place. Charlie's life is going nowhere fast. A divorced substitute teacher living with his cat in a house his siblings want to sell, all he wants is to open a pub downtown, if only the bank will approve his loan. Then his long-lost uncle Jake dies and leaves his supervillain business (complete with island volcano lair) to Charlie. But becoming a supervillain isn't all giant laser death rays and lava pits.

The millions of people around the world who loved What If? still have questions, and those questions are getting stranger. Thank goodness xkcd creator Randall Munroe is here to help. Planning to ride a fire pole from the Moon back to Earth? The hardest part is sticking the landing. Hoping to cool the atmosphere by opening everyone’s freezer door at the same time? Maybe it’s time for a brief introduction to thermodynamics. Want to know what would happen if you rode a helicopter blade, made a lava lamp out of lava, or jumped on an erupting geyser? Okay, if you insist.

Alexander Grant is a little too good at a few too many things. Two dozen martial arts. Twice that many languages. Chess, the piano, sports, forging excused absences, you name it. He graduated high school top of his class 17 times. Of course, no one knows any of this. Not that he wants to go unnoticed. It’s just safer that way.