Lindsay Kantha Souvannarath, 23, of Geneva, Ill., and Randall Steven Shepherd, 21, of Halifax are each charged with conspiracy to commit murder, conspiracy to commit arson, illegal possession of dangerous weapons and making a threat through social media.
None of the allegations against them has been proven in court.
The preliminary inquiry is scheduled for three days and is being held under a publication ban that prohibits reporting what is heard in Halifax provincial court. It was scheduled to resume on Wednesday.
Outside court, Crown prosecutor Mark Heerema said the two accused face a jury trial in Nova Scotia Supreme Court.
"It's been conceded by the defence that there is enough evidence in this matter to warrant a trial," he added.
"We would expect that shortly after this preliminary is completed, we'll be proceeding to the Supreme Court of Nova Scotia to begin the process of seeking trial dates."
The defence is asking questions of certain witnesses at the preliminary inquiry to assist in their preparation for trial, Heerema said.
He said 11 witnesses are expected to testify at the preliminary hearing.
Shepherd's lawyer, Roger Burrill, confirmed outside court that defence has conceded there is enough evidence to proceed to trial.
A Crown document alleges the offences took place between Jan. 6 and Valentine's Day.
The Crown alleges they involved the Halifax Shopping Centre and were carried out in concert with James Lee Gamble, a 19-year-old man found dead in his Halifax home.
Police allege the plot could have resulted in mass casualties at the shopping centre on Valentine's Day.
They have said Souvannarath and Shepherd were arrested at the airport in Halifax on Feb. 13 after she arrived there and met him.
Note to readers: This is a corrected story. A previous version said Randall Steven Shepherd was 20 years old.