Three brothers and their little sister discover a mysterious box in a hidden cave near their home. Inside, four pieces of gold that unite to form a magic medallion that transports the children to Ancient Greece. There they meet one of the greatest rulers of all time, Alexander the Great. Desperate to return to their own time, the children must find the secret to the mysterious medallion and discover how to control it to make sure they can get home. But an evil wizard has other plans for he wants the magical pieces of gold for himself to increase his own power and reputation. The children follow Alexander across strange lands becoming a part of history as they join the great general on his amazing exploits all the while trying hard to make sure the evil wizard does them no harm for if he gets his hands on their medallion they will be trapped in time forever.