The second series of the compelling US legal drama continues. In this week’s instalment, an explosion at a university chemistry laboratory kills one girl and injures another. Suspicion first falls on a misfit student who fits the profile of a killer, until evidence leads Reyes to a spoilt rich kid seeking revenge on an ex-girlfriend.

Stark and his team arrive at an LA university where a huge explosion ripped through a chemistry lab the night before. One girl is dead, while her roommate has been injured. “Class is in session kids – mad bomber 101,” says Stark to his team. “Failure is not an option.”

It is not long before a suspect emerges – a troubled chemical engineering scholarship student called Michael Hackford who seems to fit the profile of a killer. A threatening letter in Hackford’s handwriting, found at the scene, shows that he had the desire to hurt the other students, while files on his home computer reveal that he knew how to make bombs.

After initial questioning proves inconclusive, Reyes escorts Hackford back to the dorm where he will be kept under police surveillance, only to find that the boy’s door has been kicked in and his room vandalised. Hackford explains that he hates life at college and struggles to fit in with the other, wealthier students who think him something of a freak. He admits writing the letter, but claims he did it a year ago and would never harm anybody.

However, things change when cops find traces of explosive material in the suspect’s room along with a report that such material recently went missing from Deering’s, an LA construction company. Reyes goes back to Hackford’s dorm with the cops to make the arrest, only to find the boy hanging from a rope. Luckily, they are in time to save his life and he is rushed to hospital. When he is well enough to talk, he assures Reyes that he is not guilty – and the lawyer believes him. “I don’t think he did it,” he tells his boss. “You’ve got 24 hours to find a new suspect,” responds Stark. “And Danny – you’d better be right.”

Things begin to look better for Hackford when it emerges that the explosives found in his room differ from those used in the bomb; lab tests prove that the letter recovered from the scene was indeed a year old; and the school psychologist says that Hackford is not the violent type.

The real breakthrough comes when Raina and Isaac discover the true target of the bombing. A teaching assistant called Joe had been regularly meeting with his new girlfriend, Jamie, in the chemistry lab. Their meetings were always conducted late at night to avoid Jamie’s unhinged ex-boyfriend who had been stalking her ever since their break-up. This ex, Kyle Deering, turns out to be the son of the rich owner of the company from the which the explosives went missing. A search of Kyle’s belongings unearths blueprints of the university, pipe cutters and explosives. “I’m about to say something you’ll probably never hear again, so listen closely,” Stark tells Reyes as they arrest Deering. “You were right and I was... less right.”

As the trial opens, Stark presents the jury with his version of events. “A spoilt rich kid used to getting what he wants seeks revenge on a young woman who rejects him,” he says. But the suspect’s father, Greg, has hired his son an expensive defence attorney who uses psychological profiling to suggest that Hackford is more likely to be guilty. Hackford is called as a witness and provoked into losing his temper by the defence, but some smart talking by Reyes puts Deering back in the frame. Deering’s ex, Jamie, then takes the stand and reels off the names of several girls stalked by Deering.

The case looks to be balanced on a knife edge, until the mayor takes Stark aside. It seems the suspect’s powerful father makes regular political contributions and has made a generous financial offer to the parents of the bomb victims. “You’re not going to be able to buy your son out of this one,” Stark tells Greg. But, with pressure from the mayor to end the case, is Stark’s confidence in the system misplaced?