Set in 1997 in Saanich, Canada, the show tracks the disappearance and murder of Reena Virk—a fourteen-year-old girl who went missing after attending a party. Under the Bridge is based on a true story, which author Rebecca Godfrey told in her book of the same name.

The destruction of the bridge as depicted in the film is also entirely fictional. In fact, two bridges were built: a temporary wooden bridge and a permanent steel/concrete bridge a few months later. Both bridges were used for two years, until they were destroyed by Allied bombing.

Seth Dawson Seth is an insecure follower, seeking approval from the rebellious Adam as he tries to find a path to adulthood. He imitates Adam's cigarette smoking and clothing style while asking Adam's advice on how to be cool. He suffers the violent consequences of Adam's reckless behavior, cowardice, and lies.

This story is about a boy named Seth and a boy named Adam. Seth wanted to be as cool as Adam so he bought a denim jacket and tried to make it look like he has been in many fight just like Adam. One day they were smoking on a bridge and scaring people. Seth didn't smoke so he held it to his mouth.