- For the episode of the same name, see The Undertaking.
- "The Undertaking, which we set for ourselves, is only months from fruition. There's hope on the horizon for everyone in Starling. We won't fail this city."
- —Malcolm Merlyn[src]
The Undertaking, also referred to as "The Glades Earthquake", was a partially successful plan laid down by the powerful businessman Malcolm Merlyn and the other members of the organization Tempest to rid Starling City of the Glades. The plan was a major obstacle to the Hood and his first great defeat, as the Glades were partly laid to waste.
After the death of his wife around 1993, Malcolm visited Nanda Parbat. While there, he trained under the mentorship of a man from whom he learned his fighting skills. This man was later revealed to be Al-Owal, a member of the League of Assassins.
Malcolm at first tried a more peaceful approach on saving The Glades, by leveraging benefactors with their illegal activities and keep their names on The List. Malcolm eventually lost patience with its slow progress and decided on a new Undertaking.
In late 2007, Malcolm met with a number of associates, among them Robert Queen and Frank Chen. He discussed his plan to level the Glades with a particular device. Later, when Robert questioned him as to whether it was a good idea or not, Malcolm revealed his wife's horrible death whilst in the Glades. Robert disagrees with Malcolm's proposed Undertaking, which would involve leveling the Glades and killing thousands of people in an effort to rebuild the area and remove the crime. As a result, Malcolm had a bomb planted on the Queen's Gambit just before Robert and Oliver set off.
In 2012, the shipwrecked billionaire and former playboy Oliver Queen is rescued from Lian Yu and brought back to civilization. He begins to work as a vigilante archer in Starling City, hunting the names on "The List" which brought about Malcolm's attention. Malcolm ordered a man to kill Oliver, thinking he was the Hood, but when it was proven that he wasn't, he gave up, though not before getting threats from Moira.
At an awards ceremony, which he attended with his albeit reluctant son, Malcolm was given an award for his philanthropy and charitable nature, his contribution to making Starling City better. As he was giving his speech, the lights were turned off by the Chinese Triad. Malcolm quickly exited and found Tommy, and the two made it up to his office. Malcolm explained to Tommy about his safe room, and proceeded to open the door to it. However, before he could admit to his son his alter ego as The Dark Archer, Malcolm was shot from afar by Deadshot, who had been tasked with his assassination. Before Malcolm died, the Hood arrived and was able to convince Tommy to give his father a blood transfusion, in order to rid his body of curare poison laced in the bullet. At first, Tommy did not believe the Hood. This forced the Hood to reveal to Tommy that the Hood was Oliver Queen, Tommy's best friend. Due to the Hood, Malcolm Merlyn woke up in a hospital bed some time later. Moira Queen visited, and Malcolm asked her to find his would-be killer, who was hired, unbeknownst to him, by Moira.  Ultimately Team Arrow found out about the Undertaking and sought to stop it, capturing Moira Queen to obtain information.  Oliver contacted wayward police Detective Quentin Lance and told him of Malcolm's plans, but Detective Quentin was suspended for associating himself with the Arrow. Quentin went to the Glades to stop the Markov Device with Felicity Smoak's help. Despite Quentin disarming the device and Oliver defeating Malcolm, the Undertaking partly succeeded due to the unsuspected existence of a second device. 
While Merlyn was successful in devastating half of the Glades, the plan did not bring the intended results. Crime continued to prosper in the now-ruined Glades, with new gangsters, such as Xavier Reed taking over the destabilized district. The Undertaking has ruined Moira Queen's reputation, and turned Ra's al Ghul's anger towards Malcolm Merlyn, who operated in defiance of the League's laws, even though through their typical methods. As Merlyn discovered that Danny Brickwell murdered his wife and that the first man he ever murdered was innocent, he realised that his Undertaking was for nothing and began to regret this mistake. Merlyn himself compared the Undertaking to a much more devastating H.I.V.E. project known as Genesis. 
- Tommy Merlyn
- Ryan Doucette
- David Maclean
- Ken Rabehl
- Baker's sister
- Colton's sister
- Aglin's wife
- Jeff Deveau's wife
- 8 of Roy Harper's friends
- 487 other unnamed victims