Sirius writes to Harry again, warning him to stay safe and to just get through the [third task].

The Day of the Third Task
At breakfast the morning off the [third task], a new Rita Skeeter article appears in the [Daily Prophet], naming Harry as "disturbed and dangerous." Hermione seems to figure out how Rita is getting her information, and dashes off quickly to the [library], and McGonagall invites Harry to come with the other champions to meet their families as Ron heads off for his final exam.
Though Harry dawdles, not wanting to face up to the fact that his family has certainly not come to see the [third task], he is eventually called into the next room where Molly Weasley and Bill are waiting to surprise him. They talk for a bit about their memories of [Hogwarts], and head off for a tour with Harry.
Amos Diggory stops Harry to gloat about Cedric and take his frustration over the [Daily Prophet] out on Harry.
Harry spends an enjoyable morning with Molly and Bill, and over lunch points out to Mrs. Weasley that Hermione is not, in fact, his girlfriend (which substantially warms Mrs. Weasley towards her once again). Finally, he is called down for the [third task], and walks out of the [Great Hall] with [Bagman].
Finally the stadium fills in and the [third task] begins. Harry races through the maze, periodically running into the other [champions] as he makes his way past a [boggart], an [anti-gravity mist], and a Blast-Ended Skrewt. He surprisingly catches [Krum] torturing Cedric and stops him, and after an encounter with a [sphinx], runs into Cedric and an [acromantula], which they defeat together - and they soon take the cup together as well, and are pulled out of the maze.
Chapter 32 - "Flesh, Blood, and Bone" - In which Harry and Cedric are transported to a graveyard, encountering Voldemort. Cedric is killed, Harry is tied to Riddle's tombstone, and Wormtail resurrects Voldemort.
Alarmed, Harry and Cedric find themselves in a graveyard with someone approaching, and before they know what's happening, Cedric is killed and Harry is bound to a tombstone - Tom Riddle's - by Wormtail. Wormtail then pulls out an enormous [cauldron] and performs a complex spell, which Harry soon realizes means that Lord Voldemort has returned.
Chapter 33 - "The Death Eaters" - In which Voldemort summons the Death Eaters, chastises them, and reveals his plans, explaining how he came back to life.
With Harry tied up, Voldemort takes action, calling his Death Eaters to return to his side. They do so, and he welcomes them back, though he also expresses his anger that they did not seek him out. He then tells his version of the story of his downfall and of his return, tortures Harry, and then demands that Harry be untied.