Spoiler: Who is the Killer in A Good Girl's Guide to Murder?

Mildly intriguing but uneven. That's how the majority of viewers describe A Good Girl's Guide to Murder, a new British series adapted from Holly Jackson's award-winning young adult book of the same name.

This is backed up by the show's ratings. A Good Girl's Guide to Murder has an IMDb score of 6.9/10 and a 71% audience rating on Rotten Tomatoes. Not so rotten, but not exactly fresh either. That's probably why many viewers can't get through the story of a high school amateur detective investigating a five-year-old murder, even though it only lasts six episodes.

Whether you're one of those viewers or just can't wait until the finale to find out who the big bad of the story is, we're here to satisfy your curiosity.

The Old Case

Let's start with a quick reminder about the case the protagonist is investigating. Imagine this: a local schoolgirl, Andie Bell, goes missing. The search turns up nothing, but a few days later, her boyfriend Sal Singh commits suicide after sending a text confessing to the murder.

Five years later, Pippa 'Pip' Fitz-Amobi (played by Wednesday star Emma Myers) still can't believe that Sal, who was always kind to her, could have killed Andie. So she sets out to right the wrong and prove his innocence as part of her qualifying project.

What awaits her is an immersion into the life of a small town, where idyllic houses are surprisingly home to dozens of teenagers who routinely organize so-called calamity parties full of drugs, sex and dangerous individuals. After a few high-risk situations and uncomfortable interviews, Pip makes a shocking revelation: Andie had an older man as a lover.

And most importantly, the town is full of hardened criminals.

Killer Number One

A Good Girl's Guide to Murder relies heavily on common detective tropes and clichés, so if you've seen at least one episode, you've probably already guessed who's to blame. Pip has a best friend, Cara Ward, who lives with her sister and her single father, a local teacher. It is clear from the beginning that the father, Elliot Ward, is somehow connected to the case.

Sure enough, in the final episodes, Pippa finds out that Elliot was Andie's lover, which is a crime in itself. Almost immediately, the protagonist follows the man to his secret house and discovers that he is holding another young woman hostage there. The reason is that the woman knows he killed Sal Singh and then faked a suicide and a confession.

But that's not the end of the story.

Killer Number Two & Serial Sex Offender

Elliot Ward is a killer, but not THE killer. It turns out he didn't kill Andie. Well, not exactly. Five years ago, the two had a fight and he pushed her so hard that her head started bleeding. Panicked, Elliot left the room to get a first aid kit and when he returned, Andie was gone.

Pippa quickly puts two and two together and realizes that Andie must have gone home to get help. That's when the whole truth comes out. That night, Andie's younger sister, Becca, found out that Andie was the one selling drugs to Max Hastings, a local spoiled brat and serial sex abuser who drugged and took advantage of girls at calamity parties.

Becca was one of Max's victims. So when she found out that her own sister was part of his operation, she got angry and pushed her. An already injured Andie dropped dead, leaving a shocked Becca to believe she had killed the sister. To avoid punishment, Becca hid the body in an old septic tank.

While the two unwilling killers of Andie Bell are brought to justice in the finale, Max Hastings unfortunately walks free, with Pippa promising to keep an eye on him in the future.