Took my Inspire out for an early morning shoreline flight to grab some shots for a music video this morning. Perfect weather conditions. All pre-flight checks made. Totally straightforward operation. During a particularly wonderful shot, I suddenly lose signal. As per the emergency procedures, my Inspire decides to RTH and I regain control about halfway home (took her out about 300m). A quick aerial inspection leaves me a tad confused, as the camera is nowhere to be seen. I initiated a landing, and the aircraft seemed to be struggling a little, but that may have been some sudden wind. Closer inspection shows the entire camera plate is MIA. Dropped into the sea, along with the SD card that had all my glorious footage on. I'm utterly baffled how this could have happened, as the plate was entirely secure during my checks. Has this happened to anyone else?