We present the first results on the Dalitz-plot structure and improved measurements of the time-dependent C P -violation parameters of the process B 0 → K 0 S K 0 S K 0 S obtained using 468 × 10 6     B ¯¯¯ B decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The Dalitz-plot structure is probed by a time-integrated amplitude analysis that does not distinguish between B 0 and ¯¯¯ B 0 decays. We measure the total inclusive branching fraction B ( B 0 → K 0 S K 0 S K 0 S ) = ( 6.19 ± 0.48 ± 0.15 ± 0.12 ) × 10 − 6 , where the first uncertainty is statistical, the second is systematic, and the third represents the Dalitz-plot signal model dependence. We also observe evidence for the intermediate resonant states f 0 ( 980 ) , f 0 ( 1710 ) , and f 2 ( 2010 ) . Their respective product branching fractions are measured to be ( 2.70 + 1.25 − 1.19 ± 0.36 ± 1.17 ) × 10 − 6 , ( 0.50 + 0.46 − 0.24 ± 0.04 ± 0.10 ) × 10 − 6 , and ( 0.54 + 0.21 − 0.20 ± 0.03 ± 0.52 ) × 10 − 6 . Additionally, we determine the mixing-induced C P -violation parameters to be S = − 0.94 + 0.24 − 0.21 ± 0.06 and C = − 0.17 ± 0.18 ± 0.04 , where the first uncertainty is statistical and the second is systematic. These values are in agreement with the standard model expectation. For the first time, we report evidence of C P violation in B 0 → K 0 S K 0 S K 0 S decays; C P conservation is excluded at 3.8 standard deviations including systematic uncertainties.