|The Trap Door|
|Publication date||February 5, 2013|
| Preceded by|
Divide and Conquer
| Followed by|
Curse of the Ancients
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 Hystorians have 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.
Dak, Sera, and Riq warp into a cornfield in Maryland in 1850, in the middle of a storm. They take shelter in a nearby shed, where they activate the SQuare. Before they can make sense of the puzzle, however, they see a trap door move and leave the shed. A woman in a nearby house, who says she is Mrs. Hester Beeson and a Friend, but she then locks the trio in her cellar. Needless to say, they assume that Mrs. Beeson is SQ.
While they wait for food or any sort of help, they activate the SQuare in order to find the Hystorian of the time period. Unable to find the answer, Dak and Sera fall asleep. A little while later, Mrs. Beeson tells Riq, the only one awake, to get the food she is giving to the trio. However, instead, Riq, leaves the cellar, but it caught and taken away, but not before he yells out the clue to the SQuare code - Every third word.
Dak and Sera wake up, just as Riq shouts that, and decipher the code: Seek not lantern or Friends. After tomorrow's fair, visit the post office, then follow the drinking Gourdon. Meanwhile, Riq is thrown onto a cart with another slave woman Kessiah, and her two children, James and Araminta. As they are being chained up for an auction, Riq sees a poster in which Kessiah is called Kissy - a slave woman who is Riq's ancestor.
Back in the cellar, Sera creates a concoction that can unlock that trapdoor. The two kids leave the house and go to the fair, where they see the slave auction that Riq is in, and assure him that they'll get him out of there. Before the auction starts, Dak and Sera also learn that the only post office in town is actually the church. When the slave auction begins and it is Kissy’s turn, she is bought by her husband, John, a freedman. This stirs up a reaction in the crowd and Riq runs off, with the guards after him. Dak and Sera head towards the church, where they meet a Hystorian, Gamaliel. Gamaliel tells them that the ‘drinking Gourden’ they are looking for it actually the drinking gourd, aka the Big Dipper, meaning they should head north towards Baltimore. Sera, Dak, and Gamaliel agree to leave the church at night, but before that Sera looks for Riq. She finds him, but Riq refuses to come with her, saying that he’ll keep his ancestors safe and meet up with them in Baltimore.
Riq, Kissy, John, James, and Araminta go to the Choptank River, where a boat is waiting for them. Before they can board, however, they are caught and split up. Riq and James head into the woods and evade the guards, and eventually find a way to Baltimore. Meanwhile, Dak, Sera, and Gamaliel board a boat that takes them part of the way to Baltimore, but are caught by SQ. They manage to fend them off, however, and although the Infinity Ring is thrown into the ocean, Sera gets it back.
Once both groups get to Baltimore, Riq and James meet up with Dak, Sera, and Gamaliel. The five are then given a message to meet up with Kissy and the others, who are staying at the home of Kissy’s aunt’s friend, Thomas Garret. It’s a trap, however, and they are captured by a woman named Ilsa, who looks a lot like the leader of the SQ, Tilda. The five are then put in a locked room along with a large number of Hystorians. Thankfully, Sera realizes the key Dak’s parents gave him will open their shackles, and James was able to free an arm, allowing Dak and Sera to free everyone, although they are still locked in a room, but they have a plan. Ilsa, now in possession of the Infinity Ring, has no idea how to operate it, so Sera does it for her and the two of them go to the future, while the rest of the captives fight the SQ. By the time Sera and Ilsa come back, the SQ is defeated and Ilsa appears to have gone at least partially insane. The SQ defeated, the real Thomas Garret gets his house back and Sera gives him her gold chain from Bill to spend on helping slaves. Meanwhile, Riq take the SQuare and writes down his family history - now that Kissy is with John, she will never remarry and have Riq’s ancestor. In other words, Riq and all of his recent relatives are not supposed to exist.Before leaving the time period, the trio visit Harriet Tubman, aka Aunt Minty, after their version of the Civil War is over, around 1875. Harriet Tubman explains what happened in the twenty-five years or so in between. Right before they leave for Japan, the site of the next Great Break, Sera reveals that she had made a large mistake in the trip she and Ilsa made to the future - they had seen the Cataclysm.