Warriors-bound Adam Blair then hit Cronk with a cheap shot and Smith kicked the goal.
Melbourne hit party mode when Slater scored his second try, after Cronk found space.
Brisbane coach Wayne Bennett's gamble to play captain and fullback Darius Boyd was a flop. Boyd struggled to run with his ongoing hamstring problem and was replaced by Benji Marshall in the 50th minute. Kodi Nikorima went to fullback and Marshall into the halves.
The Storm led the Broncos 8-0 at halftime at after a physical and torrid 40 minutes with both sides missing try-scoring opportunities.
Smith's 18th minute penalty goal from a Broncos ruck infringement gave the home side the first points of the game.
Both sides came close to scoring after that but rival wings Suliasi Vunivalu and Corey Oates both knocked on with the tryline in sight.
The first try of the game finally came when Curtis Scott offloaded a peach of a pass in a tackle to Josh Addo-Carr in the 38th minute and the speedster burst clear to extend Melbourne's lead into the break.
The minor premiers had looked rattled throughout the first stanza as Brisbane applied a tonne of pressure.
Storm 30 (J Addo-Carr, B Slater 2, N Asofa-Solomona tries; C Smith 6 gls, T Harris gl).
Broncos 0. Ht: 8-0.