Infinity ring

Time has gone wrong, and best friends Dak Smyth and Sera Froste, together with the young Hystorian Riq, must use the infinity ring to travel back to one of the Great Breaks--a mutiny on the Santa María--to correct history and defeat the SQ.

"Dak, Sera, and Riq return to the United States and walk right into a deadly trap. The year is 1850 and the nation is divided over the issue of slavery. In these dark days, the Underground Railroad provides a light of hope, helping runaway slaves escape to freedom. But the SQ has taken control of the Underground Railroad from within. Now Dak and Sera are left wondering who to trust...while Riq risks everything to save the life of a young boy."--P....

"Europe is in the grip of the Dark Ages, but there is a light in the dark: Baghdad. The great city has become a center of learning, populated by scholars, merchants, and explorers from all across the known world. But danger lurks in the desert ... and Dak, Sera, and Riq must act fast to save the world's greatest library from utter destruction."--

They've sailed on the Santa Maria, defended famous cities from Vikings and Mongols, and come face to face with some of the greatest figures in history. Now, at long last, Dak, Sera, and Riq travel back in time to the moment it all began. Their mission: to save the life of young Alexander the Great. But they are not the only time travelers in ancient Greece. An epic battle against their most dangerous foe awaits them, and history will be written by...