The book follows the adventures of modern-day fourteen-year-old demigod Percy Jackson, the son of a mortal woman and the Greek god Poseidon.

Percy and his friends Annabeth Chase, Grover Underwood, Rachel Dare, and Tyson attempt to stop Luke Castellan and his army from invading Camp Half-Blood through Daedalus's labyrinth by trying to prevent Ariadne's string from falling into his hands.

Percy travels to Camp Half-Blood, where he learns Grover is in trouble with the Council of Cloven Elders for not having found Pan.

Annabeth is given leadership of a quest to find Daedalus and convince him not to give Ariadne's string to Luke, which would help him navigate the Labyrinth.

After speaking to him, they part ways; Tyson and Grover search for Pan, while Annabeth and Percy go to the God's forge in the volcano Mount St. Helens.

Despite being captured by Luke's minions, they eventually reach Daedalus's workshop and learn that Quintus is actually the ancient inventor, living as an automaton.

They run into Grover and Tyson, and discover the resting place of Pan, who speaks to them and passes part of his fading spirit into each of them.

The Titan army floods out of the Labyrinth and appears to be winning until Daedalus arrives with Mrs. O’Leary and Briares, who kill Kampê.

On his fifteenth birthday at summer's end, Percy receives a visit from his father Poseidon, who gives him a sand dollar, advising him to "spend it wisely".

[26] Since its release, The Battle of the Labyrinth has been translated into Bulgarian, Catalan (Valencian), Chinese, Czech, Danish, Dutch, Estonian, Finnish, French, German, Greek, Hebrew, Hungarian, Indonesian, Italian, Lithuanian, Norwegian, Persian, Polish, Portuguese, Romanian, Russian, Slovak, Slovenian, Spanish, Swedish, Thai, Turkish and Vietnamese.

"[2] Children's Literature made similar claims: "Riordan creates a masterful weaving of Greek mythology and traditional fantasy in this latest book...

Fans will enjoy the latest adventures of their favorite characters, and those picking the book up for the first time will have no trouble falling into this magical world.

Anita Burkam of Horn Book Magazine said in her review of the novel, "The melding of Greek myths with modern-day settings remains fresh and funny in this fourth installment".

[30] Publishers Weekly's starred review states, "One of Riordan's strengths is the wry interplay between the real and the surreal", adding, "the wit, rousing swordplay and breakneck pace [in this installment] will once again keep kids hooked.

"[35] The Los Angeles Times gave another positive review, calling it "a glorious, no-holds-barred adventure with great plot twists, a melding of ancient and bionic technology and a cliffhanger ending that will have fans eagerly awaiting the fifth and final showdown between gods and monsters next year.

He highlights The Battle of the Labyrinth's darker tone, more mature themes, and increased discussion of what it philosophically means for the characters to follow and support the Greek gods and Titans.

School Library Journal wrote that "[l]ike many series, the "Percy Jackson" books are beginning to show the strain of familiarity and repetition.

"[39] Nelda Brangwin of Library Media Connection wrote, "If this is the only book read in the series, readers may be confused by the storyline and profusion of mythological creatures.

AudioFile magazine praised the audiobook, raving, "Speedy introductions of familiar and new characters and previous plot summaries may briefly confuse a new listener, but fans will savor them," adding "Jesse Bernstein is on target whether he's narrating blow-by-blow accounts of Percy's sword fights or inventing cameos for various other characters: Hephaestus, who repairs a Toyota; an aged Daedalus; and Grover, Percy's slow-witted sidekick.

"[43] The work's review in The School Library Journal was also favorable, praising Bernstein for "[doing] a good job voicing Percy and his Cyclops half-brother" and "successfully [conveying] Annabeth's emotions".