PREVIEW: Mimi overhears important -- and dangerous information; Bo and Hope celebrate Zack's birthday. SUMMARY: Tony shows regret over Sami's accident. At the same time, Mimi arrives and asks Rex if he's told Tony the truth about the paternity test. Mimi puts her foot in her mouth about Sami during a conversation with Tony and Rex. Tony senses Rex's concern over this, but doesn't find out that he's really concerned about Tony finding out he's no longer a DiMera. Rex overhears Bart talking to Rolf and learns he is in town at an abandoned warehouse on the waterfront. Tony questions Bart about Rex's strange behavior. Rex tells Mimi he has something to do and leaves her at the mansion, intending to go find Rolf. Not willing to wait around all day, Mimi takes off and passes by a secret meeting between Tony/Bart and a sack full of diamonds. Tony spots her out of the corner of his eye and sends Bart after her, thinking she may have overheard something. Tony then visits Rex's room and stumbl