Mars in the 25th century: looking back, long ago, Earth colonized Mars; later Earth terraformed Mars. But longer ago, Mars didn’t need Earth’s help, thank you.
In ?: The Novel (Mars: the Novel), a nearly terrestrial band around the equator is home to New Mars Colony, ready to expand and populate the Red Planet, going full tilt with corporate and governmental backing from the Mother Planet. But strange things start appearing as terraforming proceeds and Mars becomes more Earth-like.
Mineral formations, thought to be an industrial staple and used as such, metamorphose into ferropods. What are they and why are they killing us? Ambulating plants--is that what they are? Why does the chemical within them act as a novel "temporal" neurotransmitter in the human brain? And the songs riding on the winds through the canyons--the Sonotomes, brilliant recordings laid down by the ancient Martians into the ferric oxide of the geology--are in contrast to an unexplained total absence of fossilized remains. Are they telling us something? Something long hidden, something terrifying--or something beautiful?
As questions sprout like seedlings after a shower, Earth sends her best and brightest and perhaps her somewhat flawed to research and to understand. Dr. Renee Niemann, a veterinarian, is assigned to the Veterinary Studies Division on Mars to explore why ferropods snap into people but not animals and begins to wonder if there is a ferropod with her name on it. There are machines that question the difference between “what-is” and “what-is-not,” and why “what-is” is, and why “what-is-not” isn’t. They are machines that can leap across eons for the answers. The ?berCollider has isolated the exotic chronoton particle, that quantum state vector that assigns time to all things. Gavin Atilano, Chairman of the Chronarchy, is tasked with the temporal reconciliation that will reconcile the colonists’ present with the time epoch three billion years earlier so that the living Martians of that time could be brought to us. Temporal reconciliation, however, is an experiment in progress and involves unforeseen, bizarre consequences. (Whatever could go wrong?)
Interwoven into the scientific drama is a political crisis perpetrated by some who do not want to know, who disdain knowledge, and only want what they can plunder with two hands. The treachery of the Nations of Earth liaison, Denton Walsh, subverts his mission on Mars toward despotic independence from Earth, perverting the vision of taking the best Earth has to offer another world into the worst.
There is extensive world-building, as well as detailed Martian biology, great human interaction with alien flora and fauna, and great new takes on time travel. And when you might think the breakneck political climax has sealed the deal and would make a satisfying ending in itself, there's a whole temporal crisis that concludes a very cosmic adventure, lifting the story to new heights of ethereal/surreal human destiny.