The full synopsis of Géla Babluani's13 (Tzameti) is not quite a secret in the same way as those of a lot of modern thrillers. The end is not a surprise, nor is it a twist, but for me to give it away would certainly ruin one of the film's greatest elements, which is its suspenseful first act. Sadly, the film's trailer, official plot outline and other critics are giving it away, and if you haven't already happened upon the spoilers, it may be difficult to avoid them. Just be aware that going in with knowledge of what the second act entails could make you bored for awhile.
The film opens with 22-year-old Sébastian (played by Géla's brother, Georges Babluani) starting a new roofing job, one which promises a good sum of money to help him support his poor family. After a few days of work, though, he begins to doubt whether he will be receiving his advance, let alone his total amount. Then one day Sébastian overhears his client, Godon (Philippe Passon), discuss a lucrative job he's about to undertake. The assignment, details of which Godon doesn't reveal, is hush-hush enough that its instructions are to be only partially delivered to him via post. When the envelope arrives it contains only a train ticket and a prepaid hotel bill.