The Promise

• The Promise earned a moderate 33.7 million baht (about $1 million USD) at the Thai box office in 2017, landing as the year's fourth-highest-grossing local film — solid, but not the runaway hit some summaries claim.
• Director Sophon Sakdaphisit co-wrote the genre-defining Thai horror hit Shutter (2004) before moving into the director's chair with Laddaland (2011), another film mining Thai domestic anxiety for scares, ahead of The Promise.
• The unfinished skyscraper at the center of the story wasn't a set piece — the production actually shot on location at Bangkok's real Sathorn Unique Tower, a genuine 'Ghost Tower' left half-built when the 1997 Asian financial crisis wiped out its developer.
• That same 1997 crisis is written directly into the plot: Ib's and Boum's fathers were business partners on a housing project that collapsed with the economy, and the girls' suicide pact grows straight out of watching their families' finances implode.
• Boum is played by two different actresses to bridge the twenty-year time jump — Thunyaphat Pattarateerachaicharoen as teenage Boum in 1997, Namthip Jongrachatawiboon as the haunted adult version two decades later.

Ib's spirit may not be haunting Boum out of pure vengeance so much as unfinished business: in her eyes the promise was that they'd go together, and Boum's survival is the anomaly that needs correcting, not a betrayal that needs punishing.

Boum's guilt suggests she didn't just freeze and get lucky — she may have made a conscious, self-preserving choice to live, then buried that choice for twenty years. The haunting escalating as the memory resurfaces makes Ib's ghost as much a manifestation of Boum's own conscience as an outside threat.

The tower itself functions as a kind of purgatory where a promise, once sworn, outlives the people who made it. Ib can't move on because the vow itself is unfinished, much like the building around her — making the film less about a vengeful ghost and more about the violence of a promise nobody had the right to make.

Bangkok, 1997: as the Asian financial crisis guts their families' fortunes, teenage best friends Ib and Boum climb the skeleton of an unfinished high-rise and make a suicide pact — jump together, stay together. Boum freezes at the edge and survives. Ib doesn't. Twenty years later Boum is a mother herself, raising a teenage daughter, Bell, who's never heard the story. But a broken promise doesn't expire — Ib's spirit comes home to collect, and it isn't picky about which generation pays. Sakdaphisit, who cut his teeth on Shutter, works the same suffocating dread here: locked doors, watching shadows, a construction site that never got to become anything else — and now never will. The production shot on location at Bangkok's real Sathorn Unique Tower, the notorious half-built "Ghost Tower," which gives the film's abandoned-hope backdrop an uncomfortably real edge.