Order, Supreme Court, New York County (Ira Gammerman, J.), entered April 27,1983, denying defendant’s motion for summary judgment, reversed, on the law, defendant’s motion granted, and the complaint dismissed, without costs or disbursements. If Plaintiffs seek to recover the value of gold bars they had stored in a safe deposit box rented from the defendant bank. The contents of the plaintiffs’ box and some 300 other boxes were rifled in a burglary. Sixteen months after this action was commenced plaintiffs filed a note of issue certifying that discovery proceedings had been completed. In fact, plaintiffs had conducted no discovery. I On appeal the parties do not dispute Special Term’s findings of a bailor-bailee relationship. (See Cohen v Manufacturers Safe Deposit Co., 297 NY 266; 9 NY Jur 2d, Banks, § 275.) Given that relationship, plaintiffs can make out a prima facie case of negligence by showing that they deposited the gold bars with the defendant and the latter is unable to return them. To meet this prima facie case, defendant must then show that its inability to return was caused by the burglary. If that is done, it then becomes the obligation of plaintiffs to prove that the burglary was caused by defendant’s negligence (I.C.C. Metals v Municipal Warehouse Co., 50 NY2d 657, 666; Balice v Erie R. R. Co., 208 App Div 427, 429; Leather’s Best v S.S. Mormaclynx, 451 F2d 800, 813, 814). 1 It is undisputed that plaintiffs delivered the gold bars to defendant and that the latter cannot redeliver. To overcome this prima facie case of negligence, defendant offered the affidavit of its vice-president in charge of the bank which relates his discovery of the burglary and its aftereffects and which sets forth the security precautions employed by defendant to safeguard against burglaries. The factual assertions of this affidavit are unchallenged. To meet the obligation thus thrust upon them, plaintiffs were obligated to present evidence sufficient to raise a question of fact whether the burglary occurred through any negligence of defendant. Mere conclusions or unsupported assertions are insufficient for this purpose (Zuckerman v City of New York, 49 NY2d 557, 562). Plaintiffs offered their attorney’s affidavit. Not based on personal knowledge, completely unsubstantiated, it is patently inadequate to fulfill plaintiffs’ obligation. H Plaintiffs would excuse their failure to produce evidence by arguing that the facts of defendant’s negligence lie solely in the latter’s knowledge. But it was plaintiffs’ own decision not to conduct discovery. Hence, they cannot rely on this excuse (Roche v Hearst Corp., 53 NY2d 767). Nor can plaintiffs rely on this • being a negligence action in which summary judgment is rare. Rarity notwithstanding, summary judgment should result when a party cannot raise a factual issue for trial (see Lynch vAerLingus/Irishlnt. Airlines, 81 AD2d 508). H Plaintiffs rely on Veihelmann v Manufacturers Safe Deposit Co. (303 NY 526). Their reliance would be appropriate only if this defendant’s affidavit had outlined all of the bank’s security efforts but made no mention of a burglary having taken place. As it is the reliance is misplaced because it is undisputed *944that defendant’s inability to return the gold bars is the result of a burglary. U Contrary to the “dissent’s assertion that the defendant’s affidavit fails to state that the bank’s alarm system had been activated, the affiant described the bank’s security system and stated that the bank had been “secured” at the close of the last business day prior to the burglary. Because the factual assertions of this affidavit are unchallenged there is no basis for an inference that the alarm system had not been activated. The dissent also urges that we consider on appeal an unrecorded statement that it recalls being made on the oral argument that discovery proceedings held in actions by other safe deposit box renters reveal that the alarm system had not been fully activated. Even if such evidence were record evidence, it is dehors the record on appeal and cannot be considered since it is not by its nature incontrovertible (Dunham, v Townshend, 118 NY 281, 286; People v Flack, 216 NY 123,129; Kirp v Caleb’s Path Realty Corp., 19 AD2d 744). Concur — Asch, J. P., Silverman and Lynch, JJ.