One inconvenient promise.

Two convenient deaths.

Seven days to save a quarter million people.

Climate change becomes impossible to ignore. After years of drought, Las Vegas runs out of water. Its citizens are forced to become water migrants, or "wigrants." Many make it safely to a tent settlement on Toronto's lakeshore. But, unprepared for this massive population surge, the city can offer them no more than seven days' of water.

Carla Cole, head of the global firm Axiom Water, is tasked with finding a solution. When one of the settlement's custodians is found dead, the police suspect an assassin is at work, and Cole scrambles to seize control. But when one of the wigrants is murdered . . . anyone and everyone becomes a suspect!