Halloween and a shooting have Hawaii Five-0 looking for a man carrying out experiments and turning humans into zombie-like creatures.
Catherine's surveillance job turns deadly. In order to save Kono, Adam reflects on what his best move should be.
A runaway bride is the main suspect when a wedding crasher is murdered. Danny decides where his relationship with Gabby is headed.
Ichabod and Abbie are called in to investigate the case of an unidentified boy who has turned up in town. As they investigate his background, they discover a surprising mystery.
To solve a double murder, Five-0 gets some help from a conspiracy theorist.
Jenny Mills escapes from the institution and Ichabod and Abbie set out to find her before their enemy does. In the process, they learn more about the demon they are facing.
Five-0 assists a Texas Ranger in finding his missing daughter when they cross paths with him during a murder investigation. Adam and Kono run into problems and find themselves fighting for their lives.moreless
The Sandman, another member of the army of evil, tortures the people of Sleepy Hollow by infiltrating their dreams and turning them into nightmares. When the Sandman targets Abbie, she must seek out her institutionalized sister, Jenny, and face her past.moreless
Steve and Wo Fat fight to escape from the attack on the maximum security unit. Catherine is taken hostage when Five-0 headquarters is seized. Five-0 goes behind the new SWAT Commander’s back to rescue Catherine. Kono and Adam find themselves exposed while hiding in Hong Kong.moreless
While still adjusting to his 21st century reality, Ichabod and Abbie continue on their quest to clear up Sleepy Hollow's mysteries. After a vision from Katrina, the two set out to look for a witch from the 1700s. The witch has been awakened and is intent on destroying Sleepy Hollow. Despite what happened to him, Andy Brooks is back and pursuing his own agenda.moreless
Ichabod Crane awakens in modern Sleepy Hollow and realizes that evil has came with him. While on a call Sheriff Corbin is killed by the Headless Horseman which is witnessed by Lt. Abbie Mills. With her own childhood supernatural experiences, Abbie forms an unlikely bond with Ichabod. The two of them set out to stop evil and figure out mysteries dating back to the 1700s. Captain Irving at first is reluctant to believe Ichabod's tales but soon after Ichabod's former wife Katrina gives clues about coming evil, they all start to believe that Sleepy Hollow is anything but sleepy.moreless
Five-0 is assigned by the CIA to find a missing federal prisoner after the plane he is being transported to Oahu on arrives without him, but instead has four dead bodies. After being set up for a murder, Kono finds herself on the outs again with the police force. Steve has another surprising encounter with Wo Fat. Danny reconnects with Gabrielle.moreless
Doris needs Steve's help on a clandestine mission to take back an incriminating microfiche. Kono is in jeopardy whilst getting closer to finding out Adam's secret.
Five-0 looks for kidnappers after they discover the body of the previous victim from ten years ago. Even though it might harm what she has going with Adam, Kono asks a favor of Catherine.
Things turn dangerous for a talk show host and her crew following Five-0 around when they run into Wo Fat.
Steve reflects back on his last mission in North Korea as he and Catherine recover the remains of fallen soldier.
Five-0 must determine who killed a member of a local company that is bringing sharks in closer to shore. Steve assists Kamekona in getting his helicopter license and this becomes a hot topic of discussion.moreless
A member of a local roller derby team falls to her death in front of Dog the Bounty Hunter, as he is arresting a fugitive just a few feet away. Catherine is sent in undercover as a new member of the derby team. Steve finds out that Catherine kept a secret from him involving his mother and questions whether he can trust her.moreless