"There's a body under the ice..." Sam Mason faces a chilling discovery that plunges him and his team into a whirlwind of mystery and danger. The victim, found beneath the frozen surface a local lake, holds a key in his pocket – a clue that unlocks a tangled web of secrets stretching back decades. But it gets complicated, especially when one of the last people to see the victim was mayoral candidate Marnie Wilson. Rumor has it the victim knew something that could jeopardize her outcome in the race for mayor. Now, more than ever, they have to rely on K-9 Lucy to unearth the chilling truths that will solve the case. Not everyone at the station is focused on this case, though, Kevin’s big secret is gnawing at him and it’s got him a bit distracted. Jo continues to try to convince her landlord to sell, Bridget makes a career move and deals with a secret from her past and the FBI starts digging up bodies buried behind the Webster house... except the outcome is something no one expected.