The Crossed Streams Climax (Ghostbusters) Ghostbusters (1984)

Protagonist	Peter Venkman (with the team)
Mission	Cross the streams — deliberately violate the cardinal rule to close the gate.
Runtime	105m
Climax	beat 41 · 94m · 90% into film
Wind-down	beats 42–43 · 95m–105m · 11m long
Resolution type	validation

The climax

The four men fire on Mr. Stay Puft and the Temple Gate without effect.^{b39 b40} Spengler proposes reversing the particle flow through the gate; Venkman names it — "You're saying cross the streams." They cross. The gate closes; Stay Puft burns; the team's cardinal rule has been deliberately violated, and the violation is what works.^b41 The post-midpoint approach (weaponize the prohibition; when the institution that depends on the apparatus becomes the agent of failure, deliberately violate the rule the apparatus required) is tested at the apocalyptic stakes the rooftop offers and holds.

The wind-down differs because

Beat 42 (the rubble: "I feel like the floor of a taxicab") and beat 43 (Dana and Louis emerge from the rubble; the team descends through cheering crowds; ectoplasmic kiss for Stantz; Venkman lifts Dana into Ecto-1).^{b42 b43} Diagnostic: the rooftop tested whether crossing the streams would close the gate; the descent and the cheering crowds enact the new equilibrium where the team is the city's defenders rather than its nuisance. The franchise validation in the wind-down is consequence, not test.

Why this is a validation climax

The post-midpoint approach is articulated immediately after the containment breach at the midpoint: in the holding cell and the mayor's office, Stantz reveals the Shandor antenna, Winston's "if someone asks you if you're a god, you say YES" names the operating wisdom, the team is deputized.^{b32 b35} The climb up Central Park West, the temple, the Gozer manifestation, the form-of-the-destructor — each is the new approach being practiced under increasing pressure. By the time Spengler proposes crossing the streams, the rule has already been broken in spirit (the team is no longer running containment); the literal crossing tests an already-articulated approach. Validation: realization at the midpoint, build through the climb, confirming test at the gate.