Temporal Contingency is the fourth book in the Big Sigma Series.

Trevor “Lex” Alexander’s life has been less than blessed. In the past year he’s had to battle corrupt corporations, deranged techno-terrorists, and a robotic scourge. Now he’s received the opportunity to finally return to the racing career that had been cut short by some poor decisions. One could excuse him for not wanting to be embroiled in another insane adventure when he is so close to returning to his life’s calling. Sometimes the call of duty will not be denied.

Karter Dee, a certified lunatic responsible for many of Lex’s recent woes, has discovered a threat on an unprecedented scale. He and Ma, his AI caretaker, know their plan to solve the problem will take a special mixture of competence, improvisation, and disregard for personal safety. Reluctance aside, Lex is the only man for the job. Even with the skilled pilot on the team, the scope of the problem has grown so massive that it may be unsolvable in its current state. Some would consider the situation hopeless, but any good engineer knows if you can’t find a solution, you have to change the problem.

To give human society a chance at a future, Lex, Karter, and Ma, will have to venture into the past.