Conversation so far:
What Lord Voldemort in this film?
Voldemort does not appear in Harry Potter and the Half-Blood Prince, although his presence and actions are felt.
How was his presence felt?
he once again declares war, and begins to rise to power once more.
What happens as he gains power?
He murders Amelia Bones of the Department of Magical Law Enforcement, and begins to target members of the Order of the Phoenix, including Emmeline Vance.
What happens next in the book?
Rowling uses several chapters as exposition to establish Voldemort's backstory.
How does she do this?
In a series of flashbacks, using the pensieve as a plot device, she reveals that Voldemort was the son of.
Who was he the son of?
Voldemort was the son of the witch Merope Gaunt and a Muggle called.
What happened after the discovery?
Riddle abandoned Merope before their child's birth, soon after which Merope died, just hours after giving birth.
What happens after this?
young Riddle met Dumbledore, who told him he was a wizard and arranged for him to attend Hogwarts.
Was Riddle good or bad?
Riddle was outwardly a model student, but was in reality a psychopath who takes.
What does Riddle go on to do?
He eventually murdered his father and grandparents as revenge for abandoning him.

Question: What happens next after those bad things?
Self-contained rewrite: What happens next after Riddle murders his father and grandparents?