ICS discovers that toxic sludge is being trucked across the border and dumped in the Canadian wilderness. They follow a trail to a vicious criminal gang, who gain control over Gray and his father. As Gray struggles to save his father, he sets off a chain of events which bring about the season's shocking conclusion.

The American President's upcoming visit to Canada has the ICS Squad on full alert. Working with DHS Agent Liz Carver and the Secret Service Advance Team, ICS sifts through hundreds of threats and uncovers an assassination plot by a Lebanese terrorist, working for the Iranian Revolutionary Guard. But as Slade digs deeper, he discovers the trail they've been following is an elaborate electronic smokescreen created by a sophisticated hacker. To make matters worse, an internal security leak means the real assassin is always one step ahead of the Squad.

Kessler discovers a Croatian war criminal has been granted amnesty, and must struggle with demons from his own past in Bosnia.

Kessler and Carver hover near death while Gray hunts down Layla's killers. A bloody highway shoot-out with the crime mob 'Ndrangheta has left Major Kessler and Agent Carver fighting for their lives. The Squad is forced to the sidelines, as Special Counsel Louise Tilden investigates the role of ICS in the much-publicized tragedy. Meanwhile, Gray, who has been suspended from duty, sets out to avenge the murders of Layla and his father Dougie.

Maggie becomes personally invested in the plight of two young Filipino children, victims of a human trafficking scheme.

ICS must find a sadistic kidnapper before he auctions off his 12-year-old victim on a pedophile website.

The frozen body of a Russian man is found in a railway car triggers an ICS investigating of the smuggling of blood diamonds via the Canadian north.

ICS helps a movie star enter the country with her newly adopted son: a Sudanese refugee with a dark past and an even darker secret.

Kessler, Gray, and Layla are trapped aboard a quarantined freighter with a captain who's accused of murdering stowaways.

When his daughter takes part in an anti-nuclear rally, Kessler is suspected of leaking classified information that leads directly to nuclear sabotage.

The Prime Minister of Quebec feels threatened and ICS follows the trail of a former FLQ bomber to a small town straddling the Canadian/US border.

Khali becomes personally involved in the case of Mina Diwan, a strong-willed Indian 18-year-old who arrives in Canada looking for her "runaway groom". Using a false identity, Anwar Singh has married Mina in the Punjab and stolen her family's $50,000 dowry. Unwilling to return to her strict Indian family, Mina seeks out Canadian relatives to sponsor her for citizenship, but they too disapprove of Mina's modern ways. ICS learns that one of Anwar's previous brides is missing and presumed dead. When Mina goes missing, Khali and the Squad must race to save her.

ICS Director Kessler and U.S. Agent LaGarda clash with disgruntled ex-Airborne soldiers and an elusive arms dealer while hunting for stolen military weapons.

ICS face escalating gang violence when a U.K. Tamil gang member enters the country for his son's life-saving surgery.

Sent to Afghanistan to provide border security advice, Kessler and his American companion are kidnapped by hostile forces.

ICS Agent Gray Jackson butts heads with a beautiful U.S. Homeland Security Agent when their undercover operation at a Mohawk casino goes awry.

ICS races to prevent a deadly terrorist attack in the heart of Toronto.

MI6 horns in on the ICS investigation of tainted heroin and an African drug smuggling ring.

Kessler's daughter Zoe helps Yuan Dao, China's star figure skater, escape from the Chinese Secret Service. Dao claims to be a freedom activist who will face torture and execution if returned to China. Having fallen for the skater and his story, Zoe takes Dao to ICS, where Kessler faces political pressure to hand him over to the Chinese. Zoe and Dao escape again, this time from Kessler.

A kingpin in Mexico's Los Zetas drug cartel is en route to Toronto to meet his new distributors - the ultraviolent street gang, MS-13. Ramon Esteban - the new flame of Kessler's ex-wife Terri - is a Mexican journalist whose articles on Los Zetas have put him on the cartel's hit list. When Kessler, Carver, and Gray attempt to transfer Ramon from Terri's shelter into protective custody, MS-13 launches an all-out attack. Kessler must fight back with an unlikely team of warriors.

Three American army deserters claim refugee status in Canada, and ICS must deal with the personal and political fallout.

A deadly assassin shows up in Toronto, drawing ICS into a web of international political intrigue.

Agent Bianca LaGarda escorts seventeen year-old Ali Jabir, a Canadian resident with ties to terrorists and just released from Guantanamo Bay, back to Canada. Kessler and ICS enter questionable moral territory as they use Ali as bait to capture notorious terrorist Nasim Mujab, Ali's childhood friend. Slade - assisted by CSIS agent and language expert Khalida Massi - uncovers an impending terrorist attack on Toronto. At the official inquiry into the 'Ndrangheta shoot-out, the future of ICS is at risk.

Now back on active duty, DHS Agent Liz Carver tracks a murder suspect, the notorious white-supremacist Cole Thorpe, to Canada. Kessler assigns Gray to infiltrate Thorpe's British Columbia-based neo-Nazi operation. Carver still blames Gray for the 'Ndrangheta debacle and her own injuries. When Gray learns the neo-Nazis are planning a devastating act of racial terrorism, Carver must work with him to stop it.

Kessler suspects the Canadian military is complicit in the cover-up of a scheme to smuggling cheap Afghan heroin into the country.