Grzegorz Damięcki plays Paweł Kopiński, a prosecutor whose sister was among those who disappeared that fateful evening and still hasn't been found to this day.
Given that he was a chaperone at the leisure camp from which she vanished, he feels responsible for her fate and remains desperate to find out what happened to her.
He finally gets his answer in the last episode of The Woods, which we've broken down for you below - beware, full spoilers follow.
The Woods ending explained: What happened that night at the camp?
Our first glimpse at what happened that night comes in the opening episode, which shows events from Paweł's perspective.
As a chaperone for the summer camp, he was supposed to be watching the teenage guests to ensure they keep out of trouble, but chose to flout this responsibility to be alone with his girlfriend, Laura.
They sneak off into the woods to make love but are interrupted by an ear-piercing scream from nearby, after which they scramble their clothes back on and race back to camp.
In the final episode, we discover that scream belonged to Paweł's sister, Kamila, who herself had been up to no good.
Over the past few weeks of camp, Kamila had become romantically involved with fellow campmate Daniel, while Paweł's best friend Artur had done the same with a girl named Monika.
But on the last day, one of the older chaperones, Wojtek, shows them that Daniel and Monika had actually been sleeping together the whole time.
Kamila and Artur are understandably upset, so Wojtek suggests a plan to get revenge by luring them out to the lake in the woods to go skinny dipping, before stealing their clothes so they are forced to walk back naked.
As planned, the five of them set off in the woods but things go horribly wrong. Kamila and Artur are about to steal the clothes, but they hesitate when Daniel and Monika start arguing with them.
In the resulting row, Monika calls Kamila ugly, which provokes a physical scuffle which ends when Kamila grabs Monika's throat and chokes her until she passes out.
When Kamila gets up, worried that she may have done serious damage, Wojtek goes over to the unconscious girl and cuts her throat open. It turns out that this camp chaperone is deeply disturbed and begins pointing the knife at the other three teens.
Artur grabs a knife of his own to hold Wojtek back while the others escape into the woods, before running off himself separated from the rest of the group.
Lost and alone, he hides behind a tree but begins to hear footsteps behind him. He assumes that it is Wojtek sneaking up on him, so he jumps out from behind the tree and stabs the unidentified figure multiple times, only to discover that it is actually Daniel.
He finds his way back to his hut in the camp, where Kamila is waiting for him with both of their mothers. Hearing what happened, the two women decide they must protect their children from facing murder charges, sending them into hiding in the dead of night.
The bodies of Daniel and Monika are found the next morning and a police investigation holds Wojtek responsible for both murders, as well as the disappearances of Kamila and Artur (who remain missing, presumed dead).
Is Pawel's sister dead or alive?
It's left somewhat ambiguous, but we think there's a strong chance that she is alive.
Paweł's mother did not tell him or anyone else that Kamila survived that night in the woods, but had planned to flee Warsaw with both of them soon after.
Sadly, she never got the chance. When Paweł's father got wind that she wanted to divorce him, he killed her and buried her body in the woods not far from where the other deaths occurred.
This meant that Kamila lost her only familial connection with her old life, but stayed in contact with Artur who also remained in exile under a fake name.
When Artur is found dead 25 years later, it sets Paweł on a path to finally revealing this elaborate conspiracy, which ends when Artur's grieving mother informs him of a nunnery where Kamila has been living.
The final scenes of the series see Paweł walking the grounds of the nunnery in search of his sister, coming across a woman in the final shot to whom he says: "Kamila?"
The camera cuts away before she fully turns around, meaning there is room for doubt over whether it is truly her, but the implication seems to be that he has finally found closure on the terrible night that defined his life.