Black Diamond is the first book written by Lennie Teague featuring the MI5 agent Dylan Griffin, published in 2016. The plot revolves around Griffin and his team attempting to take down Sean Iving and his company SOTIA.
In 1986, Jonathon Griffin (an MI5 agent) has been captured by the head of SOTIA - Lawrence Iving. After not telling Lawrence where a diamond is hidden, Jonathon is killed. Thirty years after, Jonathon's son, Dylan, has became an MI5 agent and has been assigned to find Jonathon's diamond before the new head of SOTIA, Sean Iving, does by the head of MI5, Andrew Baker.
Dylan and his best friend/fellow agent drove to Dylan's childhood home in Hersham, Surrey. When they arrived at the house, it is surrounded by Hersham Police cars. The duo walk to the door and knock. The head of the Hersham Police, DCI Robert Jones, answered the door. He told them that Dylan's mother Sarah had been killed. After hearing a noise upstairs, they run up to find a man climbing out of the window. They chased him into a field and Dylan killed him. On the man's ID badge, it said he worked for SOTIA. Dylan noticed a white BMW driving towards them. The passenger was aiming an AK-47 at them. They got into Dylan's car and made the BMW crash into a bush.
In London, Dylan, Michael and Robert told Baker about SOTIA. He threatened to fire them if they didn't find out what SOTIA was. They left the building and got in Dylan's car. A man on the opposite side of the road threw a cigarette into a puddle of petrol from a car crash. It caused an explosion and Dylan, Michael and Robert were stuck in the destroyed car. They were taken to St. Peter's Hospital in Chertsey.
One week later, they left the hospital. Dylan got a new blue Lamborghini Veneno and Michael got a green Ferrari 458. They drove to Sarah's murder scene. They found a note inside. It gave instructions to go to Molesey Football Club where Dylan's uncle Charles works. After digging up the pitch, Dylan saw a SOTIA worker with the next clue and fought him. He killed the worker. Dylan took the clue and read it out to everyone. It said it was in the fields people loved.
Dylan and Robert drove to Horsham to see a professor called George Smith. George was working for SOTIA and burnt the clue. Dylan and Robert fled when he dropped a candle and it set the house alight.
In Hersham, Dylan went to a pub. The bartender (an undercover SOTIA worker) tried to poison Dylan. Dylan shot him in the foot and had him arrested.
At the murder scene, Dylan found an active bomb. He evacuated with Michael, Lucy and the police officers. Robert sped down the road in his car followed by a fire engine. The firemen put the fire out and left. Dylan noticed a man in the garden - it was Sean Iving. He told them he just wants the diamond. A helicopter flew over and Sean escaped.
In London, Baker revealed to Dylan and Michael he worked for SOTIA after they noticed a memory chip inside his neck. Just as Baker was about to kill them his head blew up.
Dylan and Michael drove to the Hersham Police Station. They told Robert that Baker worked for SOTIA. Robert introduced them to his DI, Ken Smith. The four drove to Dylan's house in Burwood Park. At the house, they bought plane tickets to Spain because SOTIA was having a meeting there.
In Spain, Dylan, Michael, Robert and Ken snuck into the SOTIA meeting. After Sean killed a stubborn SOTIA member called Nick Jackson, Dylan, Michael, Robert and Ken attacked them. Sean escaped from Dylan.
Back in England, they made a plan to take down Sean and Sotia. That night, Sean found the diamond in the field where the BMW crashed.
The next day, Dylan, Lucy, Michael, Robert, Ken, the Hersham Police officers and some MI5 agents travelled to the SOTIA headquarters and split up into groups - Dylan, Lucy and Robert, Ken with the officers and Michael with the agents. After being stopped by Sean's assistant Miss White, Dylan, Lucy and Robert fight her but Lucy is killed in the process. Before dying, Lucy kills Miss White. Meanwhile, Ken and Michael started placing bombs around the building. Dylan and Robert were stopped once again by a man with metal arms known as Strong Arm. Dylan and Robert killed him by pushing him out a window.
Eventually, Dylan, Michael, Robert and Ken got into Sean's office. They were arrested by the security and Sean escaped by helicopter. Dylan managed to get his handcuffs off and get onto the helicopter. He held onto the landing skid of the chopper. The helicopter flew to Tower Bridge. Dylan and Sean had a final fight on top of the tower. Dylan kicked Sean over the edge but he hung onto a gargoyle. Sean grabbed Dylan's hands but he let go and Sean fell to his death.
Dylan got into the helicopter and killed the pilot. He flew back to the SOTIA headquarters and got Lucy's body and the diamond. After everyone escaped, they blew the building up and fled.
Two weeks later, Lucy's funeral was held at St. Peter's Church in Hersham. At the MI5 headquarters, the new director general, Brian Simmons, told Dylan, Michael, Robert and Ken that they were being knighted by the Queen.
One month after being knighted, Robert and Ken became agents for the MI5.