A system and method of cracking hydrocarbon feedstocks is provided that allows for significant flexibility in terms of the desired product yield. An integrated process includes introducing the feedstock and hydrogen into a first hydrocracking reaction zone containing a first hydrocracking catalyst to produce a first zone effluent. The first zone effluent and optionally additional hydrogen are passed to a second hydrocracking reaction zone containing a second hydrocracking catalyst to produce a second zone effluent. The second zone effluent is conveyed to a fractionating zone to at least a low boiling fraction and a high boiling fraction, and optionally one or more intermediate fractions. The bottoms fraction is passed to a fluidized catalytic cracking reaction and separation zone, from which olefins and gasoline are recovered. At least a portion of remaining cycle oil is passed from the fluidized catalytic cracking reaction and separation zone to the first and/or second hydrocracking reaction zone.